Patient attachability detection in respiratory flow therapy systems

Abstract

This application relates to patient attachment detection in respiratory flow therapy systems. Systems and methods can determine whether a patient is attached to a respiratory device (such as via a patient interface) from a flow parameter signal in the time domain. Additionally, these processes can classify the patient attachment state into one of four categories: disengaged, attaching in progress, attached, or disengaging in progress. The systems can include a non-sealing patient interface, such as a nasal cannula in nasal high flow therapy or any other patient interface. Data from the patient using the respiratory system can provide long term trends in therapy compliance and usage information and / or progress in the patient's respiratory function and / or other physiological functions.

Description

[0001] This application is a divisional application of the application for patent filed on March 4, 2020, entitled “Patient attachability detection in respiratory flow therapy systems” 202080018490.1. TECHNICAL FIELD

[0002] The present disclosure relates to methods and systems for providing respiratory flow therapy to a patient. In particular, the present disclosure relates to detecting whether a patient has attached to a respiratory flow system. BACKGROUND

[0003] Respiratory assistance devices are used to deliver a flow of gas to a user or patient in various settings such as hospitals, medical facilities, inpatient care, or home environments. Respiratory assistance or respiratory therapy devices (collectively referred to as “respiratory devices” or “respiratory apparatus”) can be used to deliver supplemental oxygen or other gases with the flow of gas, and / or to deliver heated and humidified gases with a humidification device. Respiratory devices can allow for adjustment and control of properties of the flow of gas, including flow rate, temperature, gas concentration, humidity, pressure, and the like. Sensors such as flow sensors and / or pressure sensors are used to measure properties of the flow of gas. SUMMARY

[0004] Respiratory apparatus can monitor and determine various parameters related to a patient’s use of the apparatus. The parameter data can inform a clinician of the patient’s health, use of the respiratory apparatus, and / or progress of the patient’s respiratory function. The data can also be used to improve the functionality of the respiratory apparatus itself.

[0005] Inhalation and exhalation by a patient using a respiratory apparatus can affect the flow of gas in the apparatus. This is because when a patient inhales through a patient interface such as a mask or nasal cannula, the resistance to the flow of gas in the patient interface is reduced; when the patient exhales, the resistance to the flow of gas in the patient interface is increased. Some parameters such as respiratory rate are determined by monitoring changes in the flow parameter signal due to inhalation and exhalation.

[0006] In a sealed system, such inhalation and exhalation is relatively easy to measure. However, in an unsealed system such as a nasal high flow system, it is more difficult to determine inhalation and exhalation by the patient due to the open nature of the system. It can be easy to mistake irregularities in the signal, particularly in the time domain signal, as respiratory triggering events. When the respiratory apparatus can detect a breath in the signal when there is no breath (e.g. due to the patient having detached, not breathing through the nose, and / or other reasons), the parameters determined from such analysis can be misleading.

[0007] The present disclosure provides methods of performing time domain analysis of a gas flow parameter to detect attachment and detachment of a patient to a respiratory system by determining a correlation value of data of the flow parameter and comparing the correlation value to one or more threshold values. Additionally, the methods described herein can classify a patient attachment state into one of four categories: detached, attaching, attached, or detaching.

[0008] Determinations of patient attachment state can be fed into other control functions of the respiratory device and / or other patient monitoring devices, such as, for example, to synchronize delivery of gas when the patient is attached, to interrupt oxygen delivery control and / or flow control and / or power to heating element(s) in the device when the patient has left the patient interface, to improve accuracy of determining other parameters such as respiratory rate, and / or to provide long term trends in therapy compliance and use information and / or progress in respiratory function of the patient. The processes disclosed herein can be used when the patient interface is a non-sealing device such as a nasal cannula in nasal high flow therapy or any other patient interface such as a face mask, nasal mask, nasal pillows mask, endotracheal tube, tracheostomy interface or other interface such as in continuous positive airway pressure (CPAP) therapy and / or bi-level pressure therapy.

[0009] In one configuration, a respiratory system configured to deliver respiratory therapy to a patient and provide information related to respiration of the patient can include a respiratory device including a controller, where the controller can be configured to receive data of a gas flow or a first parameter indicative of performance of a component of the device, the first parameter being indicative of respiration of the patient; determine a correlation value of the data of the first parameter by analyzing a trend in the data; and determine that the patient has attached to a patient interface of the device using the correlation value.

[0010] In one configuration, the controller can be configured to evaluate the correlation value of a subset of the data of the first parameter.

[0011] In one configuration, the size of the subset can be selected such that a frequency in a typical respiratory frequency range produces a higher correlation than another frequency higher than the typical respiratory frequency range.

[0012] In one configuration, the size of the subset can be selected such that the subset includes data from a predetermined time span.

[0013] In one configuration, the correlation value can be determined by analyzing a correlation between the data of the first parameter and one or more feature vectors.

[0014] In one configuration, the controller can be configured to filter the correlation value over time to give a filtered correlation value.

[0015] In one configuration, the controller can be configured to determine that the patient has attached to the patient interface if the filter-related value is above a first threshold.

[0016] In one configuration, the controller can be configured to determine that the patient has attached to the patient interface if the filter-related value is above a second threshold for a set amount of time.

[0017] In one configuration, the first threshold can be higher than the second threshold.

[0018] In one configuration, once determined to have attached, the patient can be determined to have detached if the filter-related value is below a third threshold.

[0019] In one configuration, once determined to have attached, the patient can be determined to have detached if the filter-related value is below a fourth threshold for a set amount of time.

[0020] In one configuration, the third threshold can be lower than the fourth threshold.

[0021] In one configuration, the fourth threshold can be equal to the second threshold. In one configuration, the fourth threshold can be lower than the second threshold.

[0022] In one configuration, the controller can be configured to determine that the patient is in the process of attaching if the filter-related value is between the first threshold and the second threshold for less than the set amount of time, provided that the patient has not already been deemed to have attached.

[0023] In one configuration, once determined to be in the process of attaching, the patient can be determined to have detached if the related value falls below the second threshold.

[0024] In one configuration, the controller can be configured to determine that the patient is in the process of detaching if the filter-related value is between the third threshold and the fourth threshold for less than the set amount of time, provided that the patient has not already been deemed to have detached.

[0025] In one configuration, once determined to be in the process of detaching, the patient can be determined to have attached if the related value rises above the fourth threshold.

[0026] In one configuration, the controller can use the determination of whether the patient is attached to determine whether to display certain parameters.

[0027] In one configuration, the controller can receive an estimate of the patient's respiratory rate and display the respiratory rate estimate if the patient is determined to have attached.

[0028] In one configuration, the apparatus can be configured to synchronize delivery of the gas with the patient's breathing if the patient is determined to be attached.

[0029] In one configuration, the controller can log the time in each patient attachment state.

[0030] In one configuration, the apparatus can generate an alarm when the patient becomes detached.

[0031] In one configuration, the apparatus is configured to generate the alarm immediately after the patient becomes detached. In one example, the apparatus is configured to generate the alarm in real-time as the patient is detected to be detached.

[0032] In one configuration, the apparatus is configured to generate the alarm after a preset time (i.e. predetermined time) after the patient becomes detached.

[0033] In one configuration, the preset time can be between about 10 seconds and about 10 minutes. In one example, the apparatus can be configured to generate an alarm if the apparatus detects that the patient has been detached for the preset time. In one example, the preset time is at least 1 min.

[0034] In one example, the preset time can be between about 30 seconds and about 5 minutes.

[0035] In one example, the preset time can be between about 1 minute and about 2 minutes. In one example, the preset time can be between 2 minutes and 3 minutes. The apparatus is configured to wait a predetermined time (i.e. preset time) in order to allow the patient or medical professional to correct a nasal cannula that is being detached in the event of accidental dislodgement of the cannula. The apparatus is configured to issue an alarm if the dislodgement of the cannula is detected for the preset time in order to alert the patient and / or medical professional that the patient is not receiving a flow of gas. The alarm provides a warning in the event that the patient is not receiving treatment, thereby improving the safety of the system and reducing the likelihood of the patient not receiving treatment due to detachment.

[0036] In one configuration, the alarm can be output through a nurse call port.

[0037] In one configuration, the alarm can be accompanied by an apparatus that provides the user with an option to confirm whether the patient is still attached. The option can be presented on a graphical user interface. The option can be presented as a button or window that can be selected via the user interface.

[0038] In one configuration, the option to confirm whether the patient is still attached can be used to overrule the determination that the patient has become detached.

[0039] In one configuration, the device may pause recording of certain patient parameters only when the patient has disengaged.

[0040] In one configuration, these patient parameters may include oxygen efficiency.

[0041] In one configuration, the oxygen efficiency may be based on SpO2 and FdO2.

[0042] In one configuration, the apparatus may include a supplemental gas inlet and a valve, wherein the valve is adjustable by the controller to regulate the flow of supplemental gas through the supplemental gas inlet. In one example, the supplemental gases may be oxygen or nitrogen.

[0043] In one configuration, the controller can close the valve when the patient has been detached. This reduces the waste of supplemental gas if the patient is not attached, i.e., the patient has been detached. The controller can be configured to close the valve and can be configured to reopen the valve once the patient is detected as attached.

[0044] In one configuration, the controller may control the flow generator to achieve a certain flow rate, wherein the controller may adjust the flow rate when the patient has been weaned.The flow generator may be a blower.

[0045] In one configuration, adjusting the flow rate may include decreasing the flow rate.

[0046] In one configuration, the flow rate adjustment may include increasing the flow rate. The controller may be configured to increase the flow rate to overcome partial detachment, such as when the nasal cannula is partially removed. The increased flow rate helps continue to provide breathing gas to the patient so that the patient can receive respiratory therapy. In one example, the respiratory therapy may be high-flow therapy. Even if the patient interface is partially removed and detected as detached, the increased flow rate can still deliver a sufficient amount of gas to the patient.

[0047] In one configuration, the increase in flow may continue for an initial period of time.

[0048] In one configuration, the initial time may be between about 10 seconds and about 10 minutes.

[0049] In one configuration, the initial time may be between about 30 seconds and about 5 minutes.

[0050] In one configuration, the initial time may be between about 1 minute and about 2 minutes.

[0051] In one configuration, the controller can reduce the flow when the patient is still determined to have disengaged after the initial period. The reduction in flow after the initial period can help to protect the flow generator (e.g. blower) from overworking. This can be useful if the respiratory treatment device is operating using a battery. Turning off the blower or reducing the flow can help to conserve battery power.

[0052] In one configuration, the data for the first parameter can comprise an absolute value of the first parameter. In one configuration, the data for the first parameter can comprise a change in the first parameter.

[0053] In one configuration, the change can be determined by subtracting a target value of the first parameter from a measured value of the first parameter. In one configuration, the change can be determined by subtracting an estimated influence of a second parameter from a measured value of the first parameter.

[0054] In one configuration, the first parameter can be flow. In one configuration, the first parameter can be pressure.

[0055] In one configuration, the second parameter can be motor speed. In one configuration, the second parameter can be pressure.

[0056] In one configuration, the system can be a non-sealed system.

[0057] In one configuration, the patient interface can comprise a nasal cannula or a tracheostomy interface.

[0058] In one configuration, the system can be configured to deliver nasal high flow therapy.

[0059] In one configuration, the system can be a sealed system.

[0060] In one configuration, the system can comprise the patient interface, the patient interface being a mask, a nasal mask, an endotracheal tube, or a tracheostomy interface.

[0061] In one configuration, the system can comprise a humidifier configured to humidify a flow of gas to the patient.

[0062] In one configuration, the controller is configured to reduce power to the humidifier when the patient has disengaged.

[0063] In one configuration, the controller is configured to turn off power to the humidifier when the patient has disengaged. In one configuration, the humidifier includes a heater plate and a humidification chamber. When in an operational configuration, the chamber is positioned on the heater plate. The controller is configured to turn off power to the heater plate if the patient is detected as disengaged. If the device is operated using a battery, this saves battery power. Turning off the power also protects the chamber from overheating or damage due to prolonged heating. In addition, this also helps to maintain the condition of the heater plate and chamber. In addition, turning off power to the heater plate reduces the likelihood of increasing the enthalpy of the gas delivered to the patient, as there is less heating, and thus less heat in the humidification chamber.

[0064] In one configuration, the system can include a patient breathing conduit having a heating element configured to heat a flow of gas to a patient. The heating element can be a heating wire. The heating wire can be embedded within a wall of the conduit and can be helically wound. Alternatively, the heating wire can be positioned within a lumen of the conduit.

[0065] In one configuration, the controller is configured to reduce power to a heating element of the patient breathing conduit when the patient has disengaged. This is advantageous as it reduces the likelihood of the breathing conduit overheating or damaging the conduit due to heating. Reducing or turning off power to the conduit heating element (e.g. a heating wire within the conduit) can also reduce or prevent the enthalpy of the gas from being excessive.

[0066] In one configuration, the controller is configured to turn off power to a heating element of the patient breathing conduit when the patient has disengaged. Turning off the power has similar advantages as above.

[0067] In one configuration, the system can include a display configured to receive and display information from one or more processors relating to whether the patient is attached to the system.

[0068] In one configuration, a method of determining disengagement and / or attachment of a patient from a respiratory system configured to deliver respiratory therapy to a patient and also configured to provide information relating to the patient's breathing can include using a controller of a respiratory device: receiving data of a flow of gas or a first parameter indicative of the patient's breathing or representative of a performance of a component of the device; determining a correlation value of the data of the first parameter by analyzing a trend in the data; and using the correlation value to determine that the patient has attached to a patient interface of the system.

[0069] In one configuration, determining can include evaluating a correlation value of a recent subset of the data of the first parameter.

[0070] In one configuration, the method can include selecting a size of the subset such that frequencies in a typical breathing frequency range produce a higher correlation than another frequency above the typical breathing frequency range.

[0071] In one configuration, the size of the subset can be selected such that the subset includes data from a predetermined time span.

[0072] In one configuration, determining the correlation value can include analyzing a correlation between the data of the first parameter and one or more feature vectors.

[0073] In one configuration, the method can further include filtering the correlation value over time to give a filtered correlation value.

[0074] In one configuration, the patient can be determined to have attached to the patient interface if the filtered correlation value is above a first threshold value.

[0075] In one configuration, the patient can be determined to have attached to the patient interface if the filtered correlation value is above a second threshold value for a set amount of time.

[0076] In one configuration, the first threshold value can be higher than the second threshold value.

[0077] In one configuration, once determined to have attached, the patient can be determined to have detached if the filtered correlation value is below a third threshold value.

[0078] In one configuration, once determined to have attached, the patient can be determined to have detached if the filtered correlation value is below a fourth threshold value for a set amount of time.

[0079] In one configuration, the third threshold value can be lower than the fourth threshold value.

[0080] In one configuration, the fourth threshold value can be equal to the second threshold value. In one configuration, the fourth threshold value can be lower than the second threshold value.

[0081] In one configuration, the patient can be determined to be in the process of attaching if the filtered correlation value is between the first threshold value and the second threshold value for less than the set amount of time, provided the patient has not already been deemed to have attached.

[0082] In one configuration, once determined to be in the process of attaching, the patient can be determined to have detached if the correlation value falls below the second threshold value.

[0083] In one configuration, if the filter correlation value is between the third threshold and the fourth threshold for less than the set amount of time, the patient may be determined to be disengaging, provided that the patient is not already considered to have disengaged.

[0084] In one configuration, once determined to be detaching, the patient may be determined to be attached if the correlation value rises above the fourth threshold.

[0085] In one configuration, the method may further include utilizing the determination of whether the patient is attached to determine whether to display certain parameters.

[0086] In one configuration, the method may further include receiving an estimate of the patient's breathing rate and displaying the breathing rate estimate if the patient is determined to be attached.

[0087] In one configuration, the method may further include synchronizing the delivery of gas by the device with the patient's breathing if the patient is determined to be attached.

[0088] In one configuration, the method may further include logging the time in each patient attachment state.

[0089] In one configuration, the method may further include generating an alarm when the patient becomes disengaged.

[0090] In one configuration, the method may further include generating the alarm after the patient becomes disengaged.

[0091] In one configuration, the method may further include generating the alarm after a preset time after the patient becomes disengaged.

[0092] In one configuration, the preset time may be between about 10 seconds and about 10 minutes.

[0093] In one configuration, the preset time may be between approximately 30 seconds and approximately 5 minutes.

[0094] In one configuration, the preset time may be between about 1 minute and about 2 minutes.

[0095] In one configuration, the method may further include outputting the alert through a nurse call port.

[0096] In one configuration, the method may further include accompanying the alert with providing the user with an option to confirm whether the patient is still attached.

[0097] In one configuration, the option to confirm whether the patient is still attached may be used to override a determination that the patient has become detached.

[0098] In one configuration, the method can further include pausing recording of certain patient parameters only when the patient has desaturated.

[0099] In one configuration, the patient parameters can include oxygen efficiency.

[0100] In one configuration, the oxygen efficiency can be based on Sp02 and Fd02.

[0101] In one configuration, the device can include a supplemental gas inlet and a valve, where the method can further include adjusting the valve by the controller to regulate a flow of supplemental gas through the supplemental gas inlet.

[0102] In one configuration, the method can further include the controller closing the valve when the patient has desaturated.

[0103] In one configuration, the method can further include the controller controlling a flow generator to achieve a flow, where the controller adjusts the flow when the patient has desaturated.

[0104] In one configuration, the adjustment of the flow can include decreasing the flow.

[0105] In one configuration, the adjustment of the flow can include increasing the flow.

[0106] In one configuration, the increase in the flow can be for an initial time period.

[0107] In one configuration, the initial time can be between about 10 seconds and about 10 minutes.

[0108] In one configuration, the initial time can be between about 30 seconds and about 5 minutes.

[0109] In one configuration, the initial time can be between about 1 minute and about 2 minutes.

[0110] In one configuration, the method can further include the controller decreasing the flow when the patient is still determined to have desaturated after the initial time period.

[0111] In one configuration, the data for the first parameter can include an absolute value of the first parameter. In one configuration, the data for the first parameter can include a change in the first parameter.

[0112] In one configuration, the method can further include determining the change by subtracting a target value for the first parameter from a measured value of the first parameter.

[0113] In one configuration, the method can further include determining the change by subtracting an estimated effect of a second parameter from a measured value of the first parameter.

[0114] In one configuration, the first parameter can be flow. In one configuration, the first parameter can be pressure.

[0115] In one configuration, the second parameter can be motor speed. In one configuration, the second parameter can be pressure.

[0116] In one configuration, the system can be a non-sealed system.

[0117] In one configuration, the system can be configured to deliver nasal high flow therapy.

[0118] In one configuration, the system can include the patient interface, which is a nasal cannula or a tracheostomy interface.

[0119] In one configuration, the system can be a sealed system.

[0120] In one configuration, the system can include the patient interface, which is a mask, a nasal mask, an endotracheal tube, or a tracheostomy interface.

[0121] In one configuration, the system can include a humidifier configured to humidify a flow of gas to the patient.

[0122] In one configuration, the method can further include the controller reducing power to the humidifier when the patient has disengaged.

[0123] In one configuration, the method can further include the controller disconnecting power to the humidifier when the patient has disengaged.

[0124] In one configuration, the system can include a patient breathing conduit having a heating element configured to heat a flow of gas to the patient.

[0125] In one configuration, the method can further include the controller reducing power to the heating element of the patient breathing conduit when the patient has disengaged.

[0126] In one configuration, the method can further include the controller disconnecting power to the heating element of the patient breathing conduit when the patient has disengaged.

[0127] In one configuration, the system can include a display configured to receive and display information from one or more processors relating to whether the patient is attached to the system.

[0128] In one arrangement, a respiratory system can be configured to deliver respiratory therapy to a patient, the system can also be configured to provide information related to the patient's breathing, the system can include a respiratory device having a controller, where the controller can be configured to receive data of a flow of gas or a first parameter indicative of performance of a component of the respiratory device, the first parameter being indicative of the patient's breathing; generate flow parameter variation data based on the data of the first parameter; select a portion of the flow parameter variation data; and generate a measure of instantaneous patient ventilation based on the portion of the flow parameter variation data.

[0129] In one arrangement, the controller can be configured to fit one or more functions to the selected portion of the flow parameter variation data, or apply one or more functions to the selected portion of the flow parameter variation data, and generating the measure of instantaneous patient ventilation can include determining an area under a curve generated by the one or more functions. In one arrangement, the controller can be configured to apply one or more functions to the selected portion of the flow parameter variation data, and wherein generating the measure of instantaneous patient ventilation includes determining an area under a curve generated by the one or more functions. The one or more functions can be a straight line(s) or a non-linear line(s) or a combination thereof. The curve generated by the one or more functions can be a straight line, a non-linear line, or a combination thereof. In one arrangement, one or more functions can be applied to the flow parameter variation data to output a specific value, such as instantaneous patient ventilation or other similar value.

[0130] In one arrangement, the first parameter can be indicative of flow rate. In one arrangement, the flow rate is total flow rate.

[0131] In one arrangement, the flow parameter variation data can be generated by subtracting a target value of the first parameter from a measured value of the first parameter.

[0132] In one arrangement, the controller can be further configured to receive data of a second parameter of the flow of gas or indicative of performance of a second component of the device, and wherein the flow parameter variation data can be generated by subtracting an estimated impact of the second parameter from a measured value of the first parameter.

[0133] In one arrangement, the second parameter can be indicative of or be motor speed.

[0134] In one arrangement, the second parameter can be indicative of or be pressure.

[0135] In one arrangement, the flow parameter variation data can be generated by subtracting a first average value of the first parameter from a second average value of the first parameter.

[0136] In one configuration, the second average can be based on a measured value of the first parameter.

[0137] In one configuration, the first average of the first parameter can be determined by applying a moving filter to the first parameter.

[0138] In one configuration, the portion of the flow parameter variation data includes data related to a time period within a predefined time period.

[0139] In one configuration, the portion of the flow parameter variation data can represent a length of time.

[0140] In one configuration, the length of time can be such that signal noise can be filtered out of the measure of instantaneous patient ventilation.

[0141] In one configuration, the length of time can be such that an expected respiratory rate causes the measure of instantaneous patient ventilation to increase.

[0142] In one configuration, the length of time can be 0.5-2 seconds.

[0143] In one configuration, the controller can be configured to perform a least squares fit to fit the one or more functions to the selected portion of the flow parameter variation data.

[0144] In one configuration, the curve generated by the one or more functions can be a straight line.

[0145] In one configuration, the curve generated by the one or more functions can be a horizontal line.

[0146] In one configuration, the one or more functions can be algebraic.

[0147] In one configuration, the one or more functions can be transcendental.

[0148] In one configuration, the one or more functions can generate a line of best fit.

[0149] In one configuration, the measure of instantaneous patient ventilation can be generated based on an area under an absolute value of the curve generated by the one or more functions.

[0150] In one configuration, the area under the curve can be determined by integrating an absolute value of the curve generated by the one or more functions.

[0151] In one arrangement, a method of generating a measure of instantaneous patient ventilation with a respiratory system that can be configured to deliver respiratory therapy to a patient can include using a controller of the respiratory device to: receive data of a flow of gas or a first parameter indicative of performance of a component of the device, the first parameter can be indicative of respiration of the patient; generate flow parameter variation data based on the data of the first parameter; select a portion of the flow parameter variation data; and generate a measure of instantaneous patient ventilation based on the portion of the flow parameter variation data.

[0152] In one arrangement, the method can further include fitting one or more functions to the selected portion of the flow parameter variation data, and wherein generating the measure of instantaneous patient ventilation can include determining an area under a curve generated by the one or more functions. In one arrangement, the method can further include applying one or more functions to the selected portion of the flow parameter variation data, and wherein generating the measure of instantaneous patient ventilation includes determining an area under a curve generated by the one or more functions.

[0153] In one arrangement, the first parameter can be indicative of or be flow. In one arrangement, the flow is total flow.

[0154] In one arrangement, the method can further include generating the flow parameter variation data, the generating can include subtracting a target value of the first parameter from a measured value of the first parameter.

[0155] In one arrangement, the method can further include receiving, using the controller of the respiratory device, data of a second parameter of the flow of gas or indicative of performance of a second component of the device, and wherein generating the flow parameter variation data can include subtracting an estimated impact of the second parameter from a measured value of the first parameter.

[0156] In one arrangement, the second parameter can be indicative of or be motor speed.

[0157] In one arrangement, the second parameter can be indicative of or be pressure.

[0158] In one arrangement, generating the flow parameter variation data can include subtracting a first average value of the first parameter from a second average value of the first parameter.

[0159] In one arrangement, the second average value can be based on measured values of the first parameter.

[0160] In one arrangement, the first average value of the first parameter can be determined by applying a median filter to the first parameter.

[0161] In one configuration, the portion of the flow parameter variation data can include data related to a time period within a predefined time period.

[0162] In one configuration, the length of time can be such that signal noise is filtered from the measure of instantaneous patient ventilation.

[0163] In one configuration, the length of time can be such that an expected respiratory rate causes the measure of instantaneous patient ventilation to increase.

[0164] In one configuration, the length of time can be 0.5-2 seconds.

[0165] In one configuration, the controller can perform a least squares fit to fit the one or more functions to the selected portion of the flow parameter variation data.

[0166] In one configuration, the curve generated by the one or more functions can be a straight line.

[0167] In one configuration, the curve generated by the one or more functions can be a horizontal line.

[0168] In one configuration, the one or more functions can be algebraic.

[0169] In one configuration, the one or more functions can be transcendental.

[0170] In one configuration, the one or more functions can generate a line of best fit.

[0171] In one configuration, the measure of instantaneous patient ventilation can be generated based on an area under an absolute value of the curve generated by the one or more functions.

[0172] In one configuration, the area under the curve can be determined by integrating an absolute value of the curve generated by the one or more functions.

[0173] In one configuration, the area under the curve can be determined by integrating an absolute value of the curve generated by the one or more functions.

[0174] In one arrangement, a respiratory system can be configured to deliver respiratory therapy to a patient, the system also configured to provide information related to the patient's breathing, the system can include a respiratory device, the respiratory device can include a controller, wherein the controller can be configured to receive data of a flow of gas or a first parameter indicative of performance of a component of the device, the first parameter can be indicative of the patient's breathing; generate flow parameter variation data based on the data of the first parameter; generate a measure of patient ventilation based on the flow parameter variation data; generate a measure of total signal fluctuation based on the flow parameter variation data; and determine patient attachment based on a comparison between the measure of patient ventilation and the measure of total signal fluctuation.

[0175] In one arrangement, the first parameter can be indicative of or be flow.

[0176] In one arrangement, the flow parameter variation data can be generated by subtracting a target value of the first parameter from a measured value of the first parameter.

[0177] In one arrangement, the controller can be further configured to receive data of a second parameter of the flow of gas or indicative of performance of a second component of the device, and wherein the flow parameter variation data can be generated by subtracting an estimated influence of the second parameter from a measured value of the first parameter.

[0178] In one arrangement, the second parameter can be indicative of or be motor speed.

[0179] In one arrangement, the second parameter can be indicative of or be pressure.

[0180] In one arrangement, the flow parameter variation data can be generated by subtracting a first average value of the first parameter from a second average value of the first parameter.

[0181] In one arrangement, the second average value can be based on measured values of the first parameter.

[0182] In one arrangement, the first average value of the first parameter can be determined by applying a moving filter to the first parameter.

[0183] In one arrangement, the controller can be further configured to generate a measure of instantaneous patient ventilation from the flow parameter variation data, and wherein the measure of patient ventilation can be generated by filtering the measure of instantaneous patient ventilation.

[0184] In one arrangement, the controller can be further configured to select a portion of the flow parameter variation data.

[0185] In one arrangement, the portion of the flow parameter variation data can represent 0.5-2 seconds.

[0186] In one configuration, the measure of instantaneous patient ventilation can be generated by fitting one or more functions to the selected portion of the flow parameter variation data and determining an area under an absolute value of a curve generated by the one or more functions. The one or more functions can be a straight line(s) or a non-linear line(s) or a combination thereof. The curve generated by the one or more functions can be a straight line, a non-linear line, or a combination thereof. In one configuration, one or more functions can be applied to the flow parameter variation data to output a particular value, such as instantaneous patient ventilation or other similar value.

[0187] In one configuration, the controller can be configured to perform a least squares fit to fit the one or more functions to the selected portion of the flow parameter variation data.

[0188] In one configuration, the curve generated by the one or more functions can be a straight line.

[0189] In one configuration, the curve generated by the one or more functions can be a horizontal line.

[0190] In one configuration, determining the area under the absolute value of the curve can include integrating the absolute value of the curve generated by the one or more functions.

[0191] In one configuration, the controller can be further configured to generate a measure of instantaneous total signal fluctuation from the flow parameter variation data, and wherein the measure of total signal fluctuation can be generated by filtering the measure of instantaneous total signal fluctuation.

[0192] In one configuration, the measure of instantaneous total signal fluctuation can be determined by taking an absolute value of the flow parameter variation data.

[0193] In one configuration, the measure of instantaneous total signal fluctuation can be determined by taking a square of the flow parameter variation data.

[0194] In one configuration, comparing the measure of patient ventilation and the measure of total signal fluctuation can include taking a ratio between the measure of patient ventilation and the measure of total signal fluctuation.

[0195] In one configuration, upon being determined to have attached, the controller can be configured to determine that the patient has detached if the ratio falls below an attachment threshold. In one configuration, upon being determined to have attached, the controller is configured to determine that the patient has attached if the ratio does not fall below an attachment threshold.

[0196] In one configuration, once determined to have detached, the controller can be configured to determine that the patient has attached if the ratio exceeds an attachment threshold.

[0197] In one configuration, once determined to have detached, the controller can be configured to determine that the patient has detached if the ratio does not exceed an attachment threshold.

[0198] In one configuration, the controller can be configured to determine that the patient has attached if the ratio is above a first threshold.

[0199] In one configuration, the controller can be configured to determine that the patient has attached if the ratio is above a second threshold for a set amount of time.

[0200] In one configuration, the first threshold can be higher than the second threshold.

[0201] In one configuration, once determined to have attached, the patient can be determined to have detached if the ratio is below a third threshold.

[0202] In one configuration, once determined to have attached, the patient can be determined to have detached if the ratio is below a fourth threshold for a set amount of time.

[0203] In one configuration, the third threshold can be lower than the fourth threshold.

[0204] In one configuration, the fourth threshold can be equal to the second threshold.

[0205] In one configuration, the fourth threshold can be lower than the second threshold.

[0206] In one configuration, the controller can be configured to determine that the patient is in the process of attaching if the ratio is between the first threshold and the second threshold for less than the set amount of time, provided that the patient has not already been deemed to have attached.

[0207] In one configuration, once determined to be in the process of attaching, the patient can be determined to have detached if the ratio falls below the second threshold.

[0208] In one configuration, the controller can be configured to determine that the patient is in the process of detaching if the ratio is between the third threshold and the fourth threshold for less than the set amount of time, provided that the patient has not already been deemed to have detached.

[0209] In one configuration, once determined to be in the process of detaching, the patient can be determined to have attached if the ratio rises above the fourth threshold.

[0210] In one arrangement, the controller can be configured to determine whether to display certain parameters using the determination of whether the patient is attached.

[0211] In one arrangement, the controller can be configured to receive an estimate of the patient's respiratory rate and display the respiratory rate estimate if the patient is determined to be attached.

[0212] In one arrangement, the respiratory device can be configured to synchronize delivery of gas with the patient's breathing if the patient is determined to be attached.

[0213] In one arrangement, the controller can be configured to log the time in each patient attachment state.

[0214] In one arrangement, the respiratory device can generate an alarm when the patient becomes detached.

[0215] In one arrangement, the device can generate the alarm immediately after the patient becomes detached.

[0216] In one arrangement, the device can generate the alarm after a preset time after the patient becomes detached.

[0217] In one arrangement, the preset time can be between about 10 seconds and about 10 minutes.

[0218] In one arrangement, the preset time can be between about 30 seconds and about 5 minutes.

[0219] In one arrangement, the preset time can be between about 1 minute and about 2 minutes.

[0220] In one arrangement, the alarm can be output through a nurse call port.

[0221] In one arrangement, the alarm can be accompanied by a device that provides the user with an option to confirm whether the patient is still attached.

[0222] In one arrangement, the option to confirm whether the patient is still attached can be used to overrule the determination that the patient has become detached.

[0223] In one arrangement, the respiratory device can only pause recording of certain patient parameters when the patient is detached.

[0224] In one arrangement, the patient parameters can include oxygen efficiency.

[0225] In one arrangement, the oxygen efficiency can be based on Sp02 and Fd02.

[0226] In one configuration, the apparatus can include a supplemental gas inlet and a valve, where the valve can be adjusted by the controller to regulate the flow of supplemental gas through the supplemental gas inlet.

[0227] In one configuration, the controller can close the valve when the patient has disengaged.

[0228] In one configuration, the controller can control a flow generator to achieve a flow rate, where the controller can adjust the flow rate when the patient has disengaged.

[0229] In one configuration, the adjustment of the flow rate can include decreasing the flow rate.

[0230] In one configuration, the adjustment of the flow rate can include increasing the flow rate.

[0231] In one configuration, the increase in the flow rate can be for an initial time period.

[0232] In one configuration, the initial time can be between about 10 seconds and about 10 minutes.

[0233] In one configuration, the initial time can be between about 30 seconds and about 5 minutes.

[0234] In one configuration, the initial time can be between about 1 minute and about 2 minutes.

[0235] In one configuration, the controller can decrease the flow rate when the patient is still determined to have disengaged after the initial time period.

[0236] In one configuration, a method of determining disengagement and / or attachment of a patient from a respiratory system, which can be configured to deliver respiratory therapy to a patient, the system can also be configured to provide information related to the patient's breathing, the method can include using a controller of a respiratory apparatus: receiving data of a flow of gas or a first parameter indicative of a performance of a component of the apparatus, the first parameter being indicative of the patient's breathing; generating flow parameter variation data based on the first parameter data; generating a measure of patient ventilation based on the flow parameter variation data; generating a measure of total signal fluctuation based on the flow parameter variation data; and determining patient attachability based on a comparison between the measure of patient ventilation and the measure of total signal fluctuation.

[0237] In one configuration, the first parameter can be indicative of or be a flow rate.

[0238] In one configuration, generating the flow parameter variation data can include subtracting a target value of the first parameter from a measured value of the first parameter.

[0239] In one configuration, the method can further include receiving, using the controller of the respiratory device, data of the gas flow or a second parameter indicative of a performance of a second component of the device; and wherein generating the flow parameter variation data can include subtracting an estimated influence of the second parameter from the measured values of the first parameter.

[0240] In one configuration, the second parameter can be indicative of or be a motor speed.

[0241] In one configuration, the second parameter can be indicative of or be a pressure.

[0242] In one configuration, generating the flow parameter variation data can include subtracting a first average of the first parameter from a second average of the first parameter.

[0243] In one configuration, the second average can be based on the measured values of the first parameter.

[0244] In one configuration, the first average of the first parameter can be determined by applying a moving filter to the first parameter.

[0245] In one configuration, the method can further include generating, using the controller of the respiratory device, a measure of instantaneous patient ventilation from the flow parameter variation data, and wherein generating the measure of patient ventilation can include filtering the measure of instantaneous patient ventilation.

[0246] In one configuration, the method can further include selecting, using the controller of the respiratory device, a portion of the flow parameter variation data.

[0247] In one configuration, the portion of the flow parameter variation data can represent 0.5-2 seconds.

[0248] In one configuration, generating the measure of instantaneous patient ventilation can include fitting one or more functions to the selected portion of the flow parameter variation data and determining an area under an absolute value of a curve generated by the one or more functions.

[0249] In one configuration, determining the area under the absolute value of the curve generated by the one or more functions can include the controller performing a least squares fit to fit the one or more functions to the selected portion of the flow parameter variation data.

[0250] In one configuration, the curve generated by the one or more functions can be a straight line.

[0251] In one configuration, the curve generated by the one or more functions can be a horizontal line.

[0252] In one configuration, the area under the absolute value of the curve can be determined by integrating the absolute value of the curve generated by the one or more functions.

[0253] In one configuration, the method can further include generating, using a controller of the respiratory device, a measure of instantaneous total signal fluctuation from the flow parameter variation data, and wherein generating the measure of total signal fluctuation can include filtering the measure of instantaneous total signal fluctuation.

[0254] In one configuration, generating the measure of instantaneous total signal fluctuation can include taking an absolute value of the flow parameter variation data.

[0255] In one configuration, generating the measure of instantaneous total signal fluctuation can include taking a square of the flow parameter variation data.

[0256] In one configuration, comparing the measure of patient ventilation and the measure of total signal fluctuation can include taking a ratio between the measure of patient ventilation and the measure of total signal fluctuation.

[0257] In one configuration, once determined to be attached, if the ratio falls below an attachment threshold, the patient can be determined to be detached.

[0258] In one configuration, once determined to be attached, if the ratio does not fall below an attachment threshold, the patient can be determined to be attached.

[0259] In one configuration, once determined to be detached, if the ratio exceeds an attachment threshold, the patient can be determined to be attached.

[0260] In one configuration, once determined to be detached, if the ratio does not exceed an attachment threshold, the patient can be determined to be detached.

[0261] In one configuration, the patient can be determined to be attached if the ratio is above a first threshold.

[0262] In one configuration, the patient can be determined to be attached if the ratio is above a second threshold for a set amount of time.

[0263] In one configuration, the first threshold can be higher than the second threshold.

[0264] In one configuration, once determined to be attached, if the ratio is below a third threshold, the patient can be determined to be detached.

[0265] In one configuration, once determined to be attached, if the ratio is below a fourth threshold for a set amount of time, the patient can be determined to be detached.

[0266] In one configuration, the third threshold can be lower than the fourth threshold.

[0267] In one configuration, the fourth threshold can be equal to the second threshold.

[0268] In one configuration, the fourth threshold can be lower than the second threshold.

[0269] In one configuration, if the ratio is between the first threshold and the second threshold for less than the set amount of time, the patient can be determined to be in the process of attaching, provided the patient has not already been deemed attached.

[0270] In one configuration, once determined to be in the process of attaching, if the ratio falls below the second threshold, the patient can be determined to have detached.

[0271] In one configuration, if the ratio is between the third threshold and the fourth threshold for less than the set amount of time, the patient can be determined to be in the process of detaching, provided the patient has not already been deemed detached.

[0272] In one configuration, once determined to be in the process of detaching, if the ratio rises above the fourth threshold, the patient can be determined to have attached.

[0273] In one configuration, the method can further include using a controller of the respiratory device to determine whether to display certain parameters based on whether the patient is attached.

[0274] In one configuration, the method can further include using a controller of the respiratory device to receive an estimate of a respiratory rate of the patient and display the respiratory rate estimate if the patient is determined to be attached.

[0275] In one configuration, the method can further include using a controller of the respiratory device to synchronize delivery of gas with respiration of the patient if the patient is determined to be attached.

[0276] In one configuration, the method can further include using a controller of the respiratory device to log time in each patient attachment state.

[0277] In one configuration, the method can further include using a controller of the respiratory device to generate an alert when the patient becomes detached.

[0278] In one configuration, the method can further include generating the alert after the patient becomes detached.

[0279] In one configuration, the method can further include generating the alert after a preset time after the patient has become detached.

[0280] In one configuration, the preset time can be between about 10 seconds and about 10 minutes.

[0281] In one configuration, the preset time can be between about 30 seconds and about 5 minutes.

[0282] In one configuration, the preset time can be between about 1 minute and about 2 minutes.

[0283] In one configuration, the method can further include outputting the alert through a nurse call port.

[0284] In one configuration, the method can further include causing the alert to be accompanied by an option to provide to a user to confirm whether the patient is still attached.

[0285] In one configuration, the option to confirm whether the patient is still attached can be to override the determination that the patient has become detached.

[0286] In one configuration, the method can further include pausing, using a controller of the respiratory device, recording of certain patient parameters only when the patient has become detached.

[0287] In one configuration, the patient parameters can include oxygen efficiency.

[0288] In one configuration, the oxygen efficiency can be based on SpO2 and FdO2.

[0289] In one configuration, the device can include a supplemental gas inlet and a valve, where the method can further include adjusting, by the controller, the valve to regulate a flow of supplemental gas through the supplemental gas inlet.

[0290] In one configuration, the method can further include the controller closing the valve when the patient has become detached.

[0291] In one configuration, the method can further include the controller controlling a flow generator to achieve a flow, where the controller is configured to adjust the flow when the patient has become detached.

[0292] In one configuration, the adjustment of the flow can include decreasing the flow.

[0293] In one configuration, the adjustment of the flow can include increasing the flow.

[0294] In one configuration, the increase in the flow can be for an initial period of time.

[0295] In one configuration, the initial time can be between about 10 seconds and about 10 minutes.

[0296] In one configuration, the initial time can be between about 30 seconds and about 5 minutes.

[0297] In one configuration, the initial time can be between about 1 minute and about 2 minutes.

[0298] In one configuration, the method can further comprise the controller decreasing the flow when the patient is still determined to have disengaged after the initial period.

[0299] In another configuration, the respiratory device comprises a controller configured to determine usage of the respiratory device based on an amount of time the patient is detected to be attached. The controller is configured to track the amount of time the patient is detected to be attached. The controller can further determine and count a number of times the patient is detected to be disengaged within a predefined period of time. The predefined period of time can be, for example, a treatment session. The controller can be configured to transmit the amount of time the patient is detected to be attached to a remote computing device, such as a server. In another configuration, the server can determine an amount of time the patient has used the respiratory device based on the amount of time or number of times the patient is detected to be attached. If the patient is detected to be attached for a predetermined period of time, the controller or server can determine the patient to be compliant with the treatment (e.g., high flow therapy). The patient detection method is used to determine compliance with the treatment, i.e., adherence to the treatment. The patient being detected to be attached can be used to determine usage of the respiratory device by the patient. The usage information or compliance information can be shared with or accessed by medical professionals via the respiratory device or via the server. BRIEF DESCRIPTION OF DRAWINGS

[0300] These and other features, aspects, and advantages of the present disclosure are described in reference to the drawings, which are intended to be illustrative rather than restrictive.

[0301] Figure 1 A respiratory system configured to provide respiratory therapy to a patient is schematically illustrated.

[0302] Figure 2 is a front view of an exemplary respiratory device with a humidification chamber in place and a raised handle / lever.

[0303] Figure 3 is a top view corresponding to Figure 2 .

[0304] Figure 4 is a right side view corresponding to Figure 2 .

[0305] Figure 5 is a left side view corresponding to Figure 2

[0306] Figure 6 is a rear view corresponding to Figure 2

[0307] Figure 7 is a front left perspective view corresponding to Figure 2

[0308] Figure 8 is a rear front perspective view corresponding to Figure 2

[0309] Figure 9 is a bottom view corresponding to Figure 2

[0310] Figure 10 shows an exemplary configuration of the air and oxygen inlet arrangement of the breathing apparatus.

[0311] Figure 11 shows another exemplary configuration of the air and oxygen inlet arrangement of the breathing apparatus.

[0312] Figure 12 is a cross-sectional view showing further details of the air and oxygen inlet arrangement of Figure 11

[0313] Figure 13 is another cross-sectional view showing further details of the air and oxygen inlet arrangement of Figure 11

[0314] Figure 14 is a longitudinal cross-sectional view showing further details of the air and oxygen inlet arrangement of Figure 11

[0315] Figure 15 is an exploded view of the upper and lower chassis components of the main housing of the breathing apparatus.

[0316] Figure 16 is a front left perspective view of the lower chassis of the main housing showing the housing for receiving the motor / sensor module sub-assembly.

[0317] Figure 17 is a first bottom side perspective view of the main housing of the breathing apparatus showing the recess for the motor / sensor module sub-assembly located inside the housing.

[0318] Figure 18 is a second bottom side perspective view of the main housing of the breathing apparatus showing the recess for the motor / sensor module sub-assembly.

[0319] Figure 19A ​​​​​​​​A block diagram of a control system that interacts with and / or provides control and guidance to components of a respiratory system is shown.

[0320] Figure 19B A block diagram of an example controller is shown.

[0321] Figure 20 A block diagram of a motor and sensor module is shown.

[0322] Figure 21 A sensing chamber of an example motor and sensor module is shown.

[0323] Figure 22 An example flowchart of evaluating instantaneous features for patient breath detection is shown.

[0324] Figures 23A-23C An example of determining whether flow parameter data is suitable for use in determining patient attachment and / or breath is shown.

[0325] Figure 23D An example flowchart of modifying flow rate data to eliminate the assumed effect of motor speed is shown.

[0326] Figure 24 An example instantaneous feature when evaluating various frequencies (without signal noise) is shown.

[0327] Figure 25A An example flowchart of determining filtered features for patient attachment determination is shown.

[0328] Figure 25B An example flowchart for determining patient attachment status using filtered features is shown.

[0329] Figure 26 An example flowchart for generating a measure value for determining patient attachment to a respiratory system is shown.

[0330] Figure 27 An example flowchart for determining patient attachment using a patient connection measure value is shown.

[0331] Figure 28 Another example flowchart for determining patient attachment status using a patient connection measure value is shown. DETAILED DESCRIPTION

[0332] While certain instances are described below, those skilled in the art will appreciate that the present disclosure extends beyond the specifically disclosed instances and / or uses and obvious modifications and equivalents thereof. Accordingly, it is intended that the scope of the disclosure disclosed herein be limited only by the following claims.

[0333] Overview of an exemplary respiratory system

[0334] A schematic view of a respiratory system 10 is provided in Figure 1 The respiratory system 10 can include a main device housing 100. The main device housing 100 can contain a flow generator 11, which can be in the form of a motor / impeller arrangement, an optional humidifier or humidification chamber 12, a controller 13, and a user interface 14. The user interface 14 can include a display and input device(s), such as button(s), a touchscreen, a combination of a touchscreen and button(s), etc. The controller 13 can include one or more hardware and / or software processors and can be configured or programmed to control components of the system, including but not limited to operating the flow generator 11 to generate a flow of gas for delivery to a patient, operating the humidifier or humidification chamber 12 (if present) to humidify and / or heat the flow of gas, receiving user input from the user interface 14 to reconfigure and / or user-defined operation of the respiratory system 10, and outputting information to the user (e.g., on the display). The user can be a patient, a healthcare professional, or other person.

[0335] With continued reference to Figure 1 The patient breathing conduit 16 can be coupled to a gas flow outlet 21 in the main device housing 100 of the respiratory system 10 and to a patient interface 17, such as a non-sealing interface like a nasal cannula with a manifold 19 and nasal prongs 18. The patient breathing conduit 16 can also be coupled to a face mask, a nasal mask, a nasal pillows mask, an endotracheal tube, a tracheostomy interface, etc.

[0336] The flow of gas can be generated by the flow generator 11 and can be humidified before being delivered to the patient via the patient breathing conduit 16 through the patient interface 17. The controller 13 can control the flow generator 11 to generate a desired flow of gas and / or control one or more valves to control the mixing of air and oxygen or other breathable gas. The controller 13 can control a heating element (if present) in the humidification chamber 12 to heat the gas to a desired temperature that achieves a desired level of temperature and / or humidity for delivery to the patient. The patient breathing conduit 16 can have a heating element 16a, such as a heating wire, to heat the flow of gas passing through to the patient. The heating element 16a can also be under the control of the controller 13.

[0337] The system 10 can use the ultrasonic transducer(s) in communication with the controller 13, flow sensor(s) such as thermistor flow sensors, pressure sensor(s), temperature sensor(s), humidity sensor(s), or other sensors to monitor characteristics of the gas flow and / or operate the system 10 in a manner that provides appropriate therapy. Gas flow characteristics can include gas concentration, flow, pressure, temperature, humidity, or others. Sensors 3a, 3b, 3c, 20, 25 such as pressure, temperature, humidity, and / or flow sensors can be placed at various locations in the main device housing 100, patient conduit 16, and / or patient interface 17. The controller 13 can receive output from the sensors to help it operate the breathing system 10 in a manner that provides appropriate therapy, such as for determining suitable target temperatures, flows, and / or pressures for the gas flow. Providing appropriate therapy can include meeting the patient's inspiratory demand.

[0338] The system 10 can include a wireless data transmitter and / or receiver or transceiver 15 to enable the controller 13 to receive data signals 8 wirelessly from operating sensors and / or control various components of the system 10. Additionally or alternatively, the data transmitter and / or receiver 15 can deliver data to a remote server or enable remote control of the system 10. The system 10 can include a wired connection, e.g., using a cable or wire, to enable the controller 13 to receive data signals 8 from operating sensors and / or control various components of the system 10.

[0339] The respiratory system 10 can include a high flow therapy device. High flow therapy discussed herein is intended to be given its typical ordinary meaning understood by those skilled in the art, which generally refers to a respiratory system that delivers a target flow of humidified breathing gas at a flow rate that is typically intended to meet or exceed the patient's inspiratory flow, via an intentionally unsealed patient interface. Typical patient interfaces include, but are not limited to, nasal or tracheal patient interfaces. Typical flow rates for adult patients generally range from, but are not limited to, about fifteen liters per minute to about sixty liters per minute or greater. Typical flow rates for pediatric users, such as neonates, infants, and children, generally range from, but are not limited to, about one liter per kilogram of user body weight per minute to about three liters per kilogram of user body weight per minute or greater. High flow therapy can also optionally include a gas mixture composition that includes supplemental oxygen and / or administration of therapeutic drugs. High flow therapy generally refers to nasal high flow oxygen therapy (NHF), humidified high flow nasal cannula oxygen therapy (HHFNC), high flow nasal cannula oxygen therapy (HFNO), high flow therapy (HFT), or tracheal high flow oxygen therapy (THF), among others. For example, in some configurations, for an adult patient, "high flow therapy" can refer to delivery of gas to the patient at a flow rate greater than or equal to about 10 liters per minute (10 LPM), such as between about 10 LPM and about 100 LPM, or between about 15 LPM and about 95 LPM, or between about 20 LPM and about 90 LPM, or between about 25 LPM and about 85 LPM, or between about 30 LPM and about 80 LPM, or between about 35 LPM and about 75 LPM, or between about 40 LPM and about 70 LPM, or between about 45 LPM and about 65 LPM, or between about 50 LPM and about 60 LPM. In some configurations, for a neonatal, infant, or child patient, "high flow therapy" can refer to delivery of gas to the patient at a flow rate greater than 1 LPM, such as between about 1 LPM and about 25 LPM, or between about 2 LPM and about 25 LPM, or between about 2 LPM and about 5 LPM, or between about 5 LPM and about 25 LPM, or between about 5 LPM and about 10 LPM, or between about 10 LPM and about 25 LPM, or between about 10 LPM and about 20 LPM, or between about 10 LPM and 15 LPM, or between about 20 LPM and 25 LPM. High flow therapy devices for adult patients, neonatal, infant, or child patients can deliver gas to the patient at a flow rate of between about 1 LPM and about 100 LPM or at a flow rate in any of the sub-ranges listed above.

[0340] High flow therapy can be effective in meeting or exceeding a patient's inspiratory demand, augmenting the patient's oxygenation, and / or reducing the work of breathing. Additionally, high flow therapy can create a washout effect in the nasopharynx such that the anatomic dead space of the upper airways is washed out by the high flow of gases in. The washout effect can create a reservoir of fresh gas available for each breath, while minimizing rebreathing of carbon dioxide, nitrogen, etc.

[0341] The patient interface for high flow therapy can be a non-sealing interface to prevent barotrauma (which can include tissue damage to the lungs or other organs of the patient's respiratory system due to a pressure differential relative to atmosphere). The patient interface can be a nasal cannula with a manifold and nasal prongs, and / or a face mask, and / or a nasal pillows mask, and / or a nasal mask, and / or a tracheostomy interface, or any other suitable type of patient interface.

[0342] Figures 2 to 18 An example respiratory device is shown with a main housing 100 of a respiratory system 10. The main housing 100 has a main housing upper chassis 102 and a main housing lower chassis 202. The main housing upper chassis 102 has an outer peripheral wall arrangement 106 (see Figure 15 ). The outer peripheral wall arrangement defines a humidifier or humidification chamber compartment 108 for receiving a removable humidification chamber 300. The removable humidification chamber 300 contains a suitable liquid, such as water, for humidifying gases that can be delivered to a patient.

[0343] In the illustrated form, the outer peripheral wall arrangement 106 of the main housing upper chassis 102 can include a substantially vertical left side outer wall 110 oriented in the front-to-rear direction of the main housing 100, a substantially vertical left side inner wall 112 oriented in the front-to-rear direction of the main housing 100, and an interconnecting wall 114 extending between and interconnecting upper ends of the left side outer wall 110 and the left side inner wall 112. The main housing upper chassis 102 can further include a substantially vertical right side outer wall 116 oriented in the front-to-rear direction of the main housing 100, a substantially vertical right side inner wall 118 oriented in the front-to-rear direction of the main housing 100, and an interconnecting wall 120 extending between and interconnecting upper ends of the right side outer wall 116 and the right side inner wall 118. The interconnecting walls 114, 120 are angled toward the respective outer edges of the main housing 100, but can alternatively be substantially horizontal or angled inwardly.

[0344] The upper chassis 102 of the main housing can further include a substantially vertical back outer wall 122. An upper portion of the upper chassis 102 of the main housing can include a forwardly angled surface 124. The surface 124 can have a recess 126 for receiving the display and user interface module 14. The display can be configured to display characteristics of the sensed gas(es) in real time. The system can display a patient detection status of the patient interface. If no patient is detected, the controller can not output or can cease to output the respiratory rate value(s) and / or other parameters for display. At block 2708, the controller can also optionally output a message that no patient is detected for display. An example of the message can be a “—” icon. An interconnecting wall 128 can extend between and interconnect an upper end of the back outer wall 122 and a rear edge of the surface 124.

[0345] A substantially vertical wall portion 130 can extend downwardly from a front end of the surface 124. A substantially horizontal wall portion 132 can extend forwardly from a lower end of the wall portion 130 to form a ledge. A substantially vertical wall portion 134 can extend downwardly from a front end of the wall portion 132 and terminate at a substantially horizontal floor portion 136 of the humidification chamber compartment 108. The left side inner wall 112, the right side inner wall 118, the wall portion 134, and the floor portion 136 together can define the humidification chamber compartment 108. The floor portion 136 of the humidification chamber compartment 108 can have a recess 138 for receiving a heater arrangement, such as a heating plate 140 or other suitable heating element(s), for heating liquid in the humidification chamber 300 for use during a humidification process.

[0346] The lower chassis 202 of the main housing can be attachable to the upper chassis 102 by suitable fasteners or integral attachment features, such as, for example, clips. The lower chassis 202 of the main housing can include a substantially vertical left side outer wall 210 oriented in the front-to-back direction of the main housing 100 and contiguous with the left side outer wall 110 of the upper chassis 102, and a substantially vertical right side outer wall 216 oriented in the front-to-back direction of the main housing 100 and contiguous with the right side outer wall 116 of the upper chassis 102. The lower chassis 202 of the main housing can further include a substantially vertical back outer wall 222 contiguous with the back outer wall 122 of the upper chassis 102.

[0347] The lower chassis 202 of the housing can have a lip 242 that is contiguous with the lip 142 of the upper chassis 102 of the housing and also forms a portion of the recess for receiving the handle portion 506 of the stem 500. The lower lip 242 can include a forwardly directed protrusion 243 that acts as a retainer for the handle portion 506 of the stem 500. Instead of the stem 500, the system can have a spring-loaded guard to hold the humidification chamber 300 in the humidification chamber compartment 108.

[0348] The bottom side of the housing lower case 202 may include a bottom wall 230. Respective interconnecting walls 214, 220, 228 may extend between the substantially vertical walls 210, 216, 222 and the bottom wall 230 and interconnect these walls and the bottom wall. The bottom wall 230 may include a grille 232 having a plurality of holes to enable liquid to be drained in the event of a leak (e.g., due to overflow) from the humidification chamber 300. The bottom wall 230 may also include an elongated front-to-back oriented slot 234. The slot 234 may also enable liquid to be drained in the event of a leak from the humidification chamber 300 without allowing the liquid to enter the electronics housing. In the illustrated configuration, the slot 234 may be wide and elongated relative to the holes in the grille 232 to maximize the draining of the liquid.

[0349] like Figures 17 and 18 As shown, the lower chassis 202 may have a motor recess 250 for receiving the motor and sensor module. The motor and sensor module may not be removable from the main housing 100. The motor and sensor module may be removable from the main housing 100, as shown. Figure 17 to Figure 18 As shown. A recessed opening 251 may be provided in the bottom wall 230 adjacent its rear edge for accommodating a motor and / or sensor module. A continuous, gas-impermeable, uninterrupted peripheral wall 252 may be integrally formed with the bottom wall 230 of the lower housing 202 and extend upward from the perimeter of the opening 251. A rear portion 254 of the peripheral wall 252 has a first height, and a front portion 256 of the peripheral wall 252 has a second height that is greater than the first height. The rear portion 254 of the peripheral wall 252 terminates in a substantially horizontal step 258, which in turn terminates in an upper auxiliary rear portion 260 of the peripheral wall 252. The front portion 256 and the upper auxiliary rear portion 260 of the peripheral wall 252 terminate in a top plate 262. Except for the airflow channel, all walls and the top plate 262 may be continuous, gas-impermeable, and uninterrupted. Thus, except for the airflow channel, the entire motor recess 250 may be gas-impermeable and uninterrupted.

[0350] The motor and sensor module may be insertable into the recess 250 and attachable to the lower chassis 202. After the motor and sensor module is inserted into the lower chassis 202, the gas flow channel tube 264 may extend through the downward extension tube 133 and be sealed by a soft seal.

[0351] Humidification chamber 300 may be fluidly coupled to device 10 by a linear sliding motion of humidification chamber 300 in a rearward direction from a position at the front of housing 100 in a direction toward the rear of housing 100 into humidification chamber compartment 108. Gas outlet port 322 may be in fluid communication with the motor.

[0352] like Figure 8 The illustrated gas inlet port 340 (humidified gas return) may include a removable L-shaped elbow. The removable elbow may further include a patient outlet port 344 for coupling to the patient conduit 16 to deliver gas to the patient interface. The gas outlet port 322, the gas inlet port 340, and the patient outlet port 344 may each include a soft seal (such as an O-ring seal or a T-seal) to provide a sealed gas passage between the device 10, the humidification chamber 300, and the patient conduit 16.

[0353] Humidification chamber gas inlet port 306 may be complementary to gas outlet port 322, and humidification chamber gas outlet port 308 may be complementary to gas inlet port 340. The axes of these ports may be parallel to each other to enable humidification chamber 300 to be inserted into chamber compartment 108 with linear movement.

[0354] The respiratory apparatus may have air and oxygen (or alternative assist gas) inlets in fluid communication with the motor to enable the motor to deliver air, oxygen (or alternative assist gas), or a mixture thereof, to the humidification chamber 300 and thereby to the patient. Figure 10 As shown, the device can have a combined air / oxygen (or alternative auxiliary gas) inlet arrangement 350. This arrangement can include a combined air / oxygen port 352 leading into the housing 100, a filter 354, and a cover 356 with a hinge 358. The gas tube can also optionally extend laterally or in another suitable direction and be in fluid communication with the oxygen (or alternative auxiliary gas) source. The port 352 can be fluidly coupled to the motor 402. For example, the port 352 can be coupled to the motor / sensor module 400 via a gas flow channel between the port 352 and an inlet hole or port in the motor and sensor module 400 (which in turn leads to the motor).

[0355] The device may have Figures 11 to 14The illustrated arrangement enables the motor to deliver air, oxygen (or alternative secondary gases) or suitable mixtures thereof to the humidification chamber 300 and thereby to the patient. This arrangement can include an air inlet 356' located in the rear wall 222 of the lower chassis 202 of the housing 100. The air inlet 356' includes a rigid plate with a suitable grating arrangement with holes and / or slots. A sound dampening foam can be disposed adjacent to the plate on the inner side of the plate. An air filter box 354' can be positioned adjacent to the air inlet 356' inside the main housing 100 and includes an air outlet port 360 for delivering filtered air to the motor via an air inlet port 404 in the motor / sensor module 400. The air filter box 354' can include a filter configured to remove particulates (e.g., dust) and / or pathogens (e.g., viruses or bacteria) from the gas stream. A soft seal, such as an O-ring seal, can be disposed between the air outlet port 360 and the air inlet port 404 in order to seal between these components. The device can include a separate oxygen inlet port 358' positioned adjacent to a side of the housing 100 at the rear end of the housing, the oxygen port 358' for receiving oxygen from an oxygen source, such as a tube-fed oxygen tank or source. The oxygen inlet port 358' is in fluid communication with a valve 362. The valve 362 can be suitably a solenoid valve to enable control of the amount of oxygen added to the gas stream delivered to the humidification chamber 300. The oxygen port 358' and valve 362 can be used with other secondary gases to control the addition of other secondary gases to the gas stream. Other secondary gases can include any one or more of a variety of gases that can be used in gas therapy, including but not limited to heliox and nitric oxide.

[0356] As Figures 13 to 16 illustrated, the housing lower chassis 202 can include suitable electronics boards, such as sensing circuit boards. The electronics boards can be positioned adjacent to the respective outer side walls 210, 216 of the housing lower chassis 202. The electronics boards can house or be in electrical communication with suitable electrical or electronic components, such as but not limited to microprocessors, capacitors, resistors, diodes, operational amplifiers, comparators, and switches. Sensors can be used with the electronics boards. The components of the electronics boards, such as but not limited to one or more microprocessors, can act as the controller 13 of the device.

[0357] One or both of the electronics boards can be in electrical communication with the electrical components of the device 10, including the display unit and user interface 14, the motor, the valve 362, and the heating plate 140, to operate the motor to provide a desired flow of gas, to operate the humidification chamber 300 to humidify and heat the gas stream to an appropriate level, and to supply an appropriate amount of oxygen (or an appropriate amount of an alternative secondary gas) to the gas stream.

[0358] An electronics board can be in electrical communication with a connector arrangement 274 that protrudes from the rear wall 122 of the upper chassis 102. The connector arrangement 274 can be coupled to an alarm, a pulse oximeter port, and / or other suitable accessories. The electronics board can also be in electrical communication with an electrical connector 276 that can also be disposed in the rear wall 122 of the upper chassis 102 to provide line power or battery power to components of the device.

[0359] As mentioned above, operational sensors, such as flow sensors, temperature sensors, humidity sensors, and / or pressure sensors can be placed in different locations in the respiratory device, patient breathing conduit 16, and / or cannula 17, such as Figure 1 The electronics board can be in electrical communication with these sensors. The output from the sensors can be received by the controller 13 to assist the controller 13 in operating the respiratory system 10 in a manner that includes providing optimal therapy that meets inspiratory demand.

[0360] As outlined above, the electronics board, as well as other electrical and electronic components, can be pneumatically isolated from the gas flow path to improve safety. This seal also prevents water ingress.

[0361] Control system

[0362] Figure 19A A block diagram 900 of an example control system 920, which can be the controller 13 in Figure 1 The control system 920 can manage the flow of gases that flow through the respiratory system that are delivered to the patient as-is. For example, the control system 920 can increase or decrease the flow rate by controlling the output of a motor speed of a blower (also referred to as a “blower motor” hereinafter) 930 or a valve 932 in a blender. The control system 920 can automatically determine a set or personalized value for the flow rate for a particular patient, as described below. The flow rate can be optimized by the control system 920 to improve the comfort and therapy of the patient.

[0363] The control system 920 can also generate audio and / or display / visual output 938, 939. For example, the flow therapy device can include a display and / or a speaker. The display can indicate to a physician any warnings or alarms generated by the control system 920. The display can also indicate control parameters that the physician can adjust. For example, the control system 920 can automatically recommend a flow rate for a particular patient. The control system 920 can also determine the respiratory state of the patient, including but not limited to generating the respiratory rate of the patient, and send it to the display, which will be described in more detail below.

[0364] The control system 920 can change the heater control output to control one or more of the heating elements (e.g., to maintain a temperature set point for the gas delivered to the patient). The control system 920 can also change the operation or duty cycle of the heating elements. The heater control outputs can include heating plate control output(s) 934 and heated breathing tube control output(s) 936.

[0365] The control system 920 may determine outputs 930-939 based on one or more received inputs 901-916. The inputs 901-916 may correspond to the outputs 930-939 received by the controller 600 ( Figure 19B The control system 920 may receive sensor inputs including, but not limited to, temperature sensor input(s) 901, flow rate sensor input(s) 902, motor speed input(s) 903, pressure sensor input(s) 904, gas fraction sensor input(s) 905, humidity sensor input(s) 906, pulse oximeter (e.g., SpO2) sensor input(s) 907, stored or user parameter(s) 908, duty cycle or pulse width modulation (PWM) input(s) 909, voltage input(s) 910, current input(s) 911, acoustic sensor input(s) 912, power input(s) 913, resistance input(s) 914, CO2 sensor(s) 915, and / or spirometer input(s) 916. The control system 920 may receive inputs from a user or stored in the memory 624 ( Figure 19B ). The control system 920 can dynamically adjust the flow rate for the patient over the patient's treatment time. The control system 920 can continuously monitor system parameters and patient parameters. Based on the disclosure herein, one of ordinary skill in the art will appreciate that any other suitable inputs and / or outputs can be used with the control system 920.

[0366] Controller

[0367] Figure 19B A controller 600 is shown (which may be Figure 1 6. Controller 600 may include programming instructions for detecting input conditions and controlling output conditions. The programming instructions may be stored in memory 624 of controller 600. The programming instructions may correspond to the methods, processes, and functions described herein. The programming instructions may be executed by one or more hardware processors 622 of controller 600. The programming instructions may be implemented using C, C++, Java, or any other suitable programming language. Some or all of the programming instructions may be implemented in dedicated circuitry 628, such as an ASIC or FPGA.

[0368] The controller 600 can also include circuitry 628 for receiving sensor signals. The controller 600 can further include a display 630 for communicating the status of the patient and the breathing assistance system. The display 630 can also display warnings and / or other alerts. The display 630 can be configured for real-time or otherwise displaying the sensed property(ies) of the gas. The controller 600 can also receive user input via a user interface such as the display 630. The user interface can include button(s) and / or dial(s). The user interface can include a touchscreen.

[0369] Motor and sensor module

[0370] Any feature of the breathing system described herein (including but not limited to the humidification chamber, the flow generator, the user interface, the controller, and the patient breathing conduit configured to couple the gas flow outlet of the breathing system to the patient interface) can be combined with any sensor module described herein.

[0371] Figure 20 A block diagram of a motor and sensor module 2000 is shown that can be received in a recess 2500 (shown) in a breathing apparatus. The motor and sensor module can include a blower 2001 that draws in room air for delivery to a patient. The blower 2001 can be a centrifugal blower. Figure 17 and Figure 18 The motor and sensor module can include a blower 2001 that draws in room air for delivery to a patient. The blower 2001 can be a centrifugal blower.

[0372] One or more sensors (e.g., Hall effect sensors) can be used to measure the motor speed of the blower motor. The blower motor can include a brushless DC motor from which the motor speed can be measured without the use of a separate sensor. For example, during operation of the brushless DC motor, a back electromotive force can be measured from an unenergized winding of the motor from which the motor position can be determined, which in turn can be used to calculate the motor speed. In addition, a motor driver can be used to measure the motor current, which can be used along with the measured motor speed to calculate the motor torque. The blower motor can include a low-inertia motor.

[0373] Room air can enter a room air inlet 2002 that enters the blower 2001 through an inlet port 2003. The inlet port 2003 can include a valve 2004 through which pressurized gas can enter the blower 2001. The valve 2004 can control the flow of oxygen into the blower 2001. The valve 2004 can be any type of valve, including a proportional valve or a two-position valve. In some embodiments, the inlet port does not include a valve.

[0374] Blower 2001 can operate at a motor speed greater than 1,000 RPM and less than 30,000 RPM, greater than 2,000 RPM and less than 21,000 RPM, or between any of the foregoing values. Operation of blower 2001 mixes the gas that enters blower 2001 through inlet port 2003. Using blower 2001 as a mixer can reduce the pressure drop that would otherwise occur in a system with a separate mixer, such as a static mixer including baffles, because mixing requires energy.

[0375] Mixed air can exit blower 2001 through conduit 2005 and enter flow path 2006 in sensor chamber 2007. A sensing circuit board with sensors 2008 can be positioned in sensor chamber 2007 such that the sensing circuit board is at least partially immersed in the gas stream. At least some of sensors 2008 on the sensing circuit board can be positioned within the gas stream to measure gas properties within the stream. After passing through flow path 2006 in sensor chamber 2007, the gas can exit 2009 to a humidification chamber.

[0376] Positioning sensors 2008 downstream of the combined blower and mixer 2001 can improve the accuracy of measurements, such as measurements of gas fraction concentrations, including oxygen concentration, on a system where the sensors are positioned upstream of the blower and / or mixer. This positioning can result in repeatable flow curves. Further, positioning the sensors downstream of the combined blower and mixer avoids a pressure drop that can otherwise occur because of the need for a separate mixer, such as a static mixer with baffles, between the inlet and the sensing system in the case where sensing occurs before the blower. A mixer can result in a pressure drop across the mixer. Positioning the sensors after the blower can allow the blower to act as a mixer, whereas a static mixer would reduce pressure, in contrast, the blower would increase pressure. Additionally, immersing at least a portion of the sensing circuit board and sensors 2008 in the flow path can improve the accuracy of measurements because immersing the sensors in the flow means that they are more subject to the same conditions, such as temperature and pressure, as the gas flow as it flows, and thus provide a better representation of the gas stream properties.

[0377] Turning to Figure 21 , the gas exiting the blower can enter flow path 402 in sensor chamber 400, which can be positioned within the motor and sensor module and can be Figure 20sensor 2007. The flow path 402 can have a curved shape. The flow path 402 can be configured to have a curved shape that does not have sharp turns. The flow path 402 can have curved ends with a more linear portion between the curved ends. The curved flow path shape can reduce pressure drop in the gas flow without reducing sensitivity of the flow measurement by partially coinciding the measurement region with the flow path to form a measurement portion of the flow path, which will be described below with reference to FIG. 5. Figures 23A-23B

[0378] A sensing circuit board 404 having sensors such as acoustic emitters and / or receivers, humidity sensors, temperature sensors, thermistors, etc. can be positioned in the sensor chamber 400 such that the sensing circuit board 404 is at least partially immersed in the flow path 402. Immersing at least a portion of the sensing circuit board and sensors in the flow path can improve the accuracy of the measurements because the sensors immersed in the flow path are more subject to the same conditions such as temperature and pressure as the gas flow, thus providing a better representation of the gas flow properties. After passing through the flow path 402 in the sensor chamber 400, the gas can be exhausted to a humidification chamber.

[0379] At least two different types of sensors can be used to measure the gas flow rate. A first type of sensor can include a thermistor, which can determine the flow rate by monitoring the heat transfer between the gas flow and the thermistor. The thermistor flow sensor can operate the thermistor at a constant target temperature within the flow as the gas flows around and past the thermistor. The sensor can measure the amount of electricity required to maintain the thermistor at the target temperature. The target temperature can be configured to be higher than the temperature of the gas flow such that more power is required to maintain the thermistor at the target temperature at higher flow rates.

[0380] ​The thermistor flow rate sensor can also maintain multiple (e.g., two, three, or more) constant temperatures on the thermistor to avoid the difference between the target temperature and the gas flow temperature being too small or too large. Multiple different target temperatures can allow the thermistor flow rate sensor to be accurate over a large temperature range of the gas. For example, the thermistor circuit can be configured to be able to switch between two different target temperatures such that the temperature of the gas flow will always fall within a certain range (e.g., not too close and not too far) from one of the two target temperatures. The thermistor circuit can be configured to operate at a first target temperature of about 50 °C to about 70 °C or about 66 °C. The first target temperature can be associated with a desired flow temperature range of about 0 °C to about 60 °C or about 0 °C to about 40 °C. The thermistor circuit can be configured to operate at a second target temperature of about 90 °C to about 110 °C or about 100 °C. The second target temperature can be associated with a desired flow temperature range of about 20 °C to about 100 °C or about 30 °C to about 70 °C.

[0381] The controller can be configured to adjust the thermistor circuit to change between at least the first target temperature mode and the second target temperature mode by connecting or bypassing resistors within the thermistor circuit. The thermistor circuit can be arranged in a Wheatstone bridge configuration including a first voltage divider arm and a second voltage divider arm. The thermistor can be located on one of the voltage divider arms. Further details of the thermistor flow rate sensor are described in PCT Application No. PCT / NZ2017 / 050119, filed September 3, 2017, which is incorporated by reference herein in its entirety.

[0382] The second type of sensor can include an acoustic sensor assembly. An acoustic sensor including an acoustic transmitter and / or receiver can be used to measure the time of flight of an acoustic signal to determine a gas velocity and / or composition that can be used in a flow therapy device. In one ultrasonic sensing (including an ultrasonic transmitter and / or receiver) topology, a driver causes a first sensor, such as an ultrasonic transducer, to generate an ultrasonic pulse in a first direction. A second sensor, such as a second ultrasonic transducer, receives the pulse and provides a measurement of the time of flight of the pulse between the first and second ultrasonic transducers. Using the time of flight measurement, the speed of sound of the gas flow between the ultrasonic transducers can be calculated by a processor or controller of the respiratory system. The second sensor can transmit a pulse in a second direction opposite to the first direction and the first sensor can receive the pulse to provide a second measurement of the time of flight, allowing the determination of a characteristic of the gas flow, such as flow rate or velocity. In another acoustic sensing topology, an acoustic pulse emitted by an acoustic transmitter, such as an ultrasonic transducer, can be received by an acoustic receiver, such as a microphone. Further details of an acoustic flow rate sensor are described in PCT Application No. PCT / NZ2016 / 050193, filed 2 December 2016, which is incorporated herein by reference in its entirety.

[0383] More accurate flow rate measurements can be determined in combination with readings from both the first type of sensor and the second type of sensor. For example, a previously determined flow rate and one or more outputs from one type of sensor can be used to determine a predicted current flow rate. The predicted current flow rate can then be updated using one or more outputs from the other of the first type of sensor and the second type of sensor in order to calculate a final flow rate.

[0384] Exemplary Patient Testing Process

[0385] As described above, when a patient breathes into a patient interface of a respiratory system through his or her nose, a breathing signal is detected in the flow rate or other flow parameter due to changes in flow resistance caused by inhalation and exhalation. The patient can become disengaged from the respiratory system so that there is no breathing signal in the gas flow parameter.

[0386] It can be advantageous for a respiratory system to be able to determine whether a patient is attached or disengaged, such as to assist a controller in determining whether a dominant frequency of a frequency analysis of a gas flow parameter is the breathing rate. Detection of a patient being disengaged can also have other applications, which will be described in more detail below. In addition to determining whether a patient is attached or disengaged from a respiratory system, it can also be helpful to understand whether a patient is previously attached and in the process of disengaging from a respiratory device, or previously disengaged from a respiratory device and in the process of attaching to a respiratory device.

[0387] The processes disclosed herein evaluate the time domain characteristics of the flow parameter data in order to determine whether the patient is attached or detached. In addition, these processes can classify the patient attachment status into one of four categories: detached, attaching, attached, or detaching.

[0388] The flow or other gas flow parameter signal can be fed through a pre-processing step. This step can allow the controller to determine whether the gas flow parameter is suitable for use in determining patient attachment, and / or to remove certain features from the flow parameter so that the flow parameter signal fed into the patient attachment detection process can be more representative of any influence of the patient's breathing on the gas flow parameter (such as flow, pressure, or other aspects). Reference is made below to Figures 23A-23D Details of the pre-processing step are described in more detail.

[0389] Determining transient features and filtered features

[0390] As noted above, it is assumed that if the patient is attached to the respiratory system and breathing through the patient interface, then fluctuations in the pre-processed flow or other flow parameter data are composed of random, uncorrelated noise and a correlated breathing signal generated by the patient. As Figure 22 As shown, the process can start with the controller receiving flow parameter data (such as unprocessed data) at step 2202. At decision step 2204, the controller can perform a pre-processing step, for example by determining whether the flow parameter data is good or suitable for use. If the data is not suitable for use, then the controller can discard the data at step 2206 and return to step 2202.

[0391] Figures 23A-23C An exemplary process for determining suitability of data is illustrated. The flow parameter can be flow rate. The flow parameter can also be pressure or other types of parameters disclosed herein. The flow parameter data can be an absolute value of the gas flow parameter. Alternatively, the flow parameter data can be a change in the gas flow parameter. The change can be determined by subtracting a target value of the gas flow parameter from a measured value of the gas flow parameter. The change can also be determined by subtracting an estimated influence of a second gas flow parameter from a measured value of a first gas flow parameter. The change can be calculated after determining that the flow parameter data is suitable for use. In one configuration, the change can also be calculated before determining that the flow parameter data is suitable for use.

[0392] As Figure 23A As shown, at step 2322, the controller can receive first flow parameter data (such as unprocessed data) at step 2322. At decision step 2324, the controller can determine whether the first flow parameter data is suitable for use. If the first flow parameter data is not suitable for use, then the controller can discard the first flow parameter data at step 2326 and return to step 2322. Figure 22different types of second flow parameter data (e.g., the flow parameter data received at step 2202). Assume that the second parameter has an effect on the first parameter. For example, motor speed, pressure, and / or oxygen flow or concentration can have an effect on gas flow that is separate from the effect of the patient’s breathing on gas flow. At decision step 2324, the controller can determine whether the assumed effect is valid. For example, the assumed effect can be valid if it is greater than a minimum threshold. If the assumed effect is not valid (such as being below the minimum threshold), it can be difficult to accurately predict the effect of the second parameter on the first parameter. Thus, at step 2328, the controller can determine that the first parameter data is not suitable for use and can discard the first parameter data, which can be the flow parameter data received at step 2202. If the assumed effect is valid (such as being greater than the minimum threshold), at step 2326, the controller can determine that the first parameter data is suitable for use. Figure 22

[0393] In the process of Figure 23B and Figure 23C the first parameter can include flow data and the second parameter(s) can include motor speed, oxygen flow, and / or oxygen concentration. In some configurations, Figure 23B and Figure 23C both of the processes of Figure 23B ​At step 2340, the controller can receive motor speed data. In order to identify a patient's breath in flow rate data, the motor needs to be running at a sufficient speed. If the motor speed is too low, it can be difficult to accurately predict the effect of motor speed on flow data, such as flow rate. Thus, at step 2342, the controller can compare the motor speed to a minimum motor speed threshold. If the motor speed is below or equal to the threshold, at step 2344, the controller can deem the flow parameter data unsuitable and can discard some or all of the flow parameter data. If the motor speed is above the threshold, at step 2346, the controller can calculate the recent change in motor speed. Changes in motor speed can cause changes in flow parameters, which make it more difficult to identify a patient's breath in flow parameter data. While the effects of motor speed can be removed from flow parameter data to some extent, large changes in motor speed can make the data too unreliable for identifying a patient's breath. Thus, at step 2348, the controller can apply a running filter to the relative change in motor speed in order to generate a first value representative of the recent relative change in motor speed. At decision step 2350, the controller can compare the first value to a first threshold. If the first value is above the first threshold, the controller can deem the flow parameter data unsuitable and can discard the flow data point at step 2344. If the first value is below the first threshold, at step 2345, the controller can deem the flow parameter data suitable.

[0394] Flow parameters, such as flow rate, can also be affected by the flow rate or concentration of supplemental gas from a supplemental gas source, such as oxygen from a supplemental oxygen source. While the steps performed in relation to the flow rate or concentration of oxygen are demonstrated with the example of using oxygen, Figure 23C but the steps performed in relation to the flow rate or concentration of oxygen can also be performed in relation to the flow rate or concentration of any other supplemental gas mixed with ambient air. At step 2352, the controller can receive oxygen flow rate data or oxygen concentration data. At step 2354, the controller can calculate the recent change in oxygen flow rate or oxygen concentration. If the flow rate or concentration of oxygen changes, the resulting change in total flow rate can make it more difficult to identify a patient's breath in the flow rate signal or other flow parameter signal. Thus, at step 2356, the controller can apply a running filter to the change in oxygen concentration or oxygen flow rate of the gas in order to generate a second value representative of the recent change in oxygen concentration or flow rate. At decision step 2358, the controller can compare the second value to a second threshold. If the second value is above the second threshold, the controller can determine that the flow parameter data is unsuitable and can discard the flow parameter data point at step 2360. If the second value is below the threshold, at step 2362, the controller can deem the flow parameter data suitable.

[0395] For the above determinations, either oxygen (or other supplemental gas) concentration data or oxygen (or other supplemental gas) flow data can be used. Oxygen concentration data can be determined using one or more sensors in the breathing apparatus, such as an ultrasonic sensor. Oxygen flow rate from the oxygen source can be determined by an oxygen gas flow rate sensor located downstream of the oxygen source.

[0396] As noted above, the flow rate (or any other flow parameter data) can also be modified to remove the effects of the motor (or other factors, such as oxygen concentration or flow) if the controller deems the data to be suitable. Modifying the gas flow parameter can involve removing the assumed effect of other variables from the gas flow parameter, such as motor speed. This assumed effect is only valid if the gas flow parameter data meets certain criteria. If these criteria are not met, the data can be discarded, as noted above.

[0397] Figure 23D An example process of modifying flow rate data to remove the effects of motor speed is shown. The effects of the motor can be estimated using the motor speed and the flow conductance. At step 2380, the controller can measure the instantaneous flow conductance. The flow conductance is approximately constant over time, and thus can be evaluated using a low pass filter. The controller uses the current motor speed and the measured flow rate to measure the instantaneous flow conductance for each iteration. At step 2382, the controller filters the instantaneous flow conductance in order to determine a filtered flow conductance.

[0398] At decision step 2384, the controller can compare the instantaneous flow conductance to the filtered flow conductance to see if the difference is significantly different. If the difference is significant, it can be that some change has occurred in the physical system, such as the attachment or detachment of a cannula. The instantaneous flow conductance can be compared to the filtered flow conductance by taking the difference of the two variables at decision step 2386 and comparing it to a minimum threshold. If the difference exceeds the threshold, the difference is considered significant, and the controller can reset the filtered flow conductance at step 2388. This reset can allow the apparatus to quickly adjust its evaluation of the flow conductance when a cannula has been attached to or detached from a patient.

[0399] At step 2390, the controller can also change the filter coefficient for the filtered flow conductance calculation based on the difference between the instantaneous flow conductance and the filtered flow conductance. This allows the filtered flow conductance to change more quickly when the variance of the flow conductance is high, such as when a cannula is first attached. The controller can then return to step 2380 to start a new iteration of the process.

[0400] If the difference does not exceed the threshold, the difference is considered insignificant, and at step 2392, the controller can evaluate the effect of the motor on the flow rate. The controller can use the filtered flow conductance and the motor speed to output an effect value. At step 2394, this value can be subtracted or otherwise removed from the flow rate data to result in pre-processed flow rate data. The pre-processed flow rate data can be more indicative of the patient's respiratory flow (although the pre-processed flow rate data can still contain signal noise).

[0401] The controller can also track the latest change in flow conductance. The change can be tracked by adding the difference between the last two instantaneous flow conductance values to a running total, which is then decayed over time. The decayed running total is filtered to obtain a filtered latest change in flow conductance. The filtered latest change in conductance can be used in other parts of the frequency analysis algorithm along with the pre-processed flow rate data.

[0402] Returning to Figure 22 If the flow parameter data is suitable for use, at step 2208, the controller can evaluate the instantaneous feature of the recent data, which can be done by analyzing whether there is a trend in the recent data. The time scale of the recent data can be fixed to be, for example, less than the minimum expected or typical respiratory period, preferably between the minimum expected or typical respiratory period and one quarter of the minimum expected or typical respiratory period, or between one half of the minimum expected or typical respiratory period and one quarter of the minimum expected or typical respiratory period, or preferably less than one half of the minimum expected or typical respiratory period, or more preferably less than one quarter of the minimum expected or typical respiratory period. The evaluation can be done by using two vectors, where the instantaneous feature is a measure of how well the recent data points correlate to one or a combination of the two vectors. The evaluation can also be done by using a single vector or more than two vectors.

[0403] If the patient is not breathing through the patient interface, random fluctuations in the pre-processed flow data can have a lower correlation to one or both of the two vectors than when the patient is breathing through the patient interface. Additionally, data of a higher frequency can have a lower correlation than data of a lower frequency because the time period of the data being evaluated will have multiple oscillations of the higher frequency. A signal that can result in a high correlation (and thus a larger instantaneous feature) is a signal with a low frequency, such as the patient's respiratory signal.

[0404] Figure 24 An example of the instantaneous feature when evaluating various frequencies of data (which can include a sine wave) is shown (in the absence of signal noise). The shaded area 2402 represents the possible values of the instantaneous feature (due to different phases of the sine wave). The solid line 2404 presents the average value of the instantaneous feature for that frequency. Continuing with the example of a sine wave, the instantaneous feature for a frequency of 0.5 Hz is 0.5, the instantaneous feature for a frequency of 1 Hz is 0, the instantaneous feature for a frequency of 2 Hz is -0.5, and the instantaneous feature for a frequency of 4 Hz is -1. Figure 22, at decision step 2210, the controller determines whether the transient characteristic is above a certain transient characteristic threshold. Figure 24 In the configuration shown, the threshold is shown as a dashed line 2406.

[0405] In one configuration, the frequency is less than 60 minutes -1 The sine wave of can have a transient signature close to 1. This frequency can be most correlated with the typical respiratory frequency of a patient (such as an adult patient). The respiratory signal can be decomposed into the fundamental (respiration) frequency and harmonics. The harmonics typically become smaller with the harmonic order (e.g., the frequency amplitude of the first harmonic is less than the fundamental frequency and the frequency amplitude of the second harmonic is less than the first harmonic). All of these harmonics contribute to the transient signature with the highest amplitude (i.e., the amplitude of the fundamental frequency) having the greatest impact. In some configurations, the threshold can be lower than 1 (e.g., Figure 24 about 0.4), so that 60 and 120min -1 Frequencies between 10 and 15 can also exceed the threshold. These frequencies may still be caused by the patient's breathing, especially in the case of infants. The higher frequencies mentioned above typically do not generate transient features above the threshold.

[0406] Return to Figure 22 If the instantaneous characteristic is above the threshold, the controller may output that breathing is detected or the patient is attached in step 2212. If the instantaneous characteristic is not above the threshold, the controller may output that breathing is not detected or the patient is detached in step 2214.

[0407] A transient feature above a transient feature threshold may indicate that a breathing patient has been attached to a patient interface (such as by being attached to a cannula). In addition, to reduce signal noise that causes transient feature fluctuations, the transient features may also be filtered before being used to determine the patient attachment state of the respiratory system.

[0408] like Figure 25A As shown, two filters can be applied to the transient signature in one process to obtain the filtered signature. The process can begin with the controller receiving flow parameter data (such as unprocessed data) at step 2502. At decision step 2504, the controller can perform a pre-processing step, such as by determining whether the flow parameter data is good or suitable for use. If the data is not suitable for use, the controller can discard the data at step 2506 and return to step 2502. If the data is suitable for use, the controller can evaluate the transient signature of the data at step 2508.

[0409] At step 2510, the controller can apply two different filters to the instantaneous feature to generate a primary filtered feature and a short filtered feature, respectively. At step 2512, the controller can use the short filtered feature to determine a filter coefficient for the primary filtered feature. At step 2514, the filtered features can be used to determine a patient attachment status, such as Figure 25B Application of the two filters causes the primary filtered feature to change more quickly when the instantaneous feature is close to 1, allowing a patient attachment determination to be made more quickly when there is a strong respiratory signal. In addition, when the patient is not breathing on a patient interface, such as an endotracheal tube, the instantaneous feature will drop close to 0, increasing the filter coefficient of the primary filtered feature and causing the primary filtered feature to change less quickly, which in turn allows a patient attachment determination to be made more quickly. The controller can take a relatively long time to determine that the patient has detached (compared to when the patient is attached and breathing via the patient interface), but can take a relatively short time to determine that the patient is attached.

[0410] It is more preferable to make an error in determining that the patient is attached when the patient is not attached to the respiratory system than to make an error in determining that the patient has detached when the patient is still attached to the respiratory system. This is partly because many algorithms for controlling the flow rate and / or motor speed of the respiratory device rely on the patient being attached in order to function. Incorrectly determining that the patient has detached can prevent these algorithms from functioning when needed. This can prevent the device from synchronizing the delivery of gas with the patient's breathing and / or reduce the effectiveness of the respiratory therapy. In addition, incorrectly determining that the patient has detached can cause discomfort to the patient who is still attached to the patient interface due to incorrect flow rates and / or motor speeds.

[0411] As Figure 26 As shown in FIG. 26, a process can be applied to flow parameter data to obtain a measure of patient ventilation and a measure of total signal fluctuation. Similar to other processes described herein, the process can begin at step 2602 with the controller receiving data of a flow parameter (which can include raw data of a first parameter or a second parameter). The flow parameter can be flow rate or a parameter indicative of flow rate. In one configuration, the flow rate can be a total flow rate, including respiratory flow rate, supplemental gas flow rate, or other flow rate. In one configuration, the flow parameter can be a direct measure of gas flow. The flow parameter can be a pressure, motor speed, or other type of parameter disclosed herein. The flow parameter can be a measure of or a parameter indicative of pressure, motor speed, or other type of parameter disclosed herein. The flow parameter can be indicative of the performance of a component of the device. At decision step 2604, the controller can perform a pre-processing step, such as by determining whether the flow parameter data is good or suitable for use. If the data is not suitable for use, the controller can discard the data at step 2606 and return to step 2602.

[0412] If the data is suitable for use, the controller can generate flow parameter variation data at step 2608. The flow parameter variation data can be determined by subtracting a target value of the flow parameter data from a measured value of the flow parameter data. The flow parameter variation data can be determined by subtracting an estimated influence of a second parameter from a measured value of a first parameter. In one configuration, the first flow parameter or first parameter is a gas flow or a parameter indicative of a gas flow. In one configuration, the second flow parameter or second parameter is a pressure, a motor speed, or another flow measure, or a parameter indicative thereof. The estimated influence of the second parameter on the first parameter can be a flow variation that can be expected based on a current value of the second parameter, such as a current motor speed. This estimated influence can assume no noise or patient interaction. The estimated influence can be calculated using the current value of the second parameter, such as the current motor speed, and a running average of a relationship between motor speed and flow, which can be used to characterize a relationship between the first flow parameter and the second flow parameter. In one configuration, the flow parameter variation data can be determined by subtracting a first average of the flow parameter data from a second average of the flow parameter data. The first average can be later in time than the second average. The first average can also be based on a longer data window than the second average. In one configuration, the second average can be based on a longer data window than the first average. The data windows can be mutually exclusive in time or overlapping in time. The data windows can involve the same length of time or different lengths of time. The first average of the flow parameter data can be determined by applying a filter or performing a moving filter to the flow parameter data. The first average of the flow parameter data can be updated constantly or continuously. The second average can be based on a measured value. The flow parameter variation data can be calculated after determining that the data is suitable for use. In one configuration, the flow parameter variation data can be calculated before determining that the data is suitable for use.

[0413] At step 2610, the controller selects a portion of the flow parameter variation data for analysis. The selected portion of the flow parameter variation data can be the last measured flow parameter variation data, or flow parameter variation data measured contemporaneously or in close temporal proximity to the analysis. The portion of flow parameter variation data can be associated with a time period within a predefined time period. The portion can be selected to obtain a data set representative of or associated with a particular length of time. Selecting a portion of the processed flow parameter data associated with a longer time period can result in more noise being reliably filtered out of the processed flow parameter data than selecting a portion of the processed flow parameter data associated with a shorter time period. However, selecting a portion of the processed flow parameter data associated with a longer time period can result in respiratory signals with higher frequencies being filtered out than selecting a portion of the processed flow parameter data associated with a shorter time period. Thus, there can be a tradeoff between filtering noise and detecting or capturing transient changes when selecting a portion of the processed flow parameter data representative of a length of time. In one configuration, it can be advantageous to select a portion of the processed flow parameter data representative of a length of time that is less than a respiratory period. In one configuration, selecting a portion of the processed flow parameter data representative of a length of time in the range of 0.5-2 seconds can provide reliability in detecting patient interaction or attachment for most expected respiratory frequencies (as well as speaking, coughing, etc.), while its length makes it unlikely that false determinations of patient attachment or interaction will be generated due to random noise. In one configuration, the selected portion of the processed flow parameter data can be less than 0.5, 0.5-1, 1-1.5, 1.5-2, 2-2.5, 2.5-3, 3-3.5, 3.5-4, 4-4.5, 4.5-5, 5-5.5, 5.5-6, or more than 6 seconds.

[0414] In one configuration, the controller selects a portion of the processed flow parameter data (or window) associated with a particular length of time prior to generating the flow parameter variation data at step 2608. In one configuration, the controller selects a portion of the processed flow parameter data (or window) associated with a particular length of time such that signal noise is filtered out of the instantaneous patient ventilation measure values, as described below. In one configuration, the controller selects a portion of the processed flow parameter data associated with a particular length of time such that expected respiratory frequencies (which can include all expected respiratory frequencies) result in an increase in the instantaneous patient ventilation measure values.

[0415] At step 2612, the controller fits one or more functions to the selected portion of the flow parameter variation data. The one or more functions can be algebraic, such as a polynomial function (e.g., constant, linear, non-linear, quadratic, cubic, etc.), a rational function, a root function, and / or other functions. The one or more functions can be transcendental, such as an exponential function, a hyperbolic function, a logarithmic function, a power function, a periodic function (e.g., a trigonometric function, etc.), and / or other functions. The controller can perform a variety of line and / or curve fitting techniques to fit the one or more functions to the selected portion of the flow parameter variation data, which can include, by way of non-limiting example techniques, regression analysis, interpolation, extrapolation, linear least squares, non-linear least squares, total least squares, simple linear regression, robust simple linear regression, polynomial regression, orthogonal regression, Deming regression, linear piecewise regression, regression dilution, and / or other techniques. The one or more functions, including at least those functions above, can generate a curve. The curve can be a straight line. The lines or curves described herein can include a plurality of curves, vertices, and / or other features. The lines described herein can be straight, angled, and / or horizontal. The lines described herein can be a best fit line.

[0416] In one configuration, the controller can perform a least squares fit of a line, which can include fitting a linear function, such as a straight line, to the selected portion of the flow parameter variation data. For example, the straight line can be represented by where m is the mean value of the line, s is the slope, and t is a linearly increasing normalized time parameter. In one configuration, t can be a linearly increasing normalized time parameter that equals negative one at the oldest data point used and one at the newest data point used. In one configuration, the controller can fit a horizontal line to the selected portion of the flow parameter variation data. The horizontal line can be a mean value of the flow parameter variation data represented or with respect to the selected portion. For example, the horizontal line can be represented by where m is the mean value.

[0417] At step 2614, the controller generates a measure of patient ventilation. The measure of patient ventilation can be primarily related to patient ventilation, but can include some noise. The controller can generate a measure of instantaneous patient ventilation (also referred to as a flow volume parameter or a volume measure) by determining an area under a function selected to fit the portion of flow parameter variation data at step 2612. In one configuration, the controller can generate a measure of instantaneous ventilation by determining an area under a curve generated by the function fitted to the flow parameter variation data at step 2612. In one configuration, the controller can generate a measure of instantaneous ventilation by determining an area under an absolute value of one or more functions at step 2612 or a curve generated by the one or more functions. This can be determined by integrating an absolute value of one or more functions at step 2612 or a curve generated by the one or more functions. In one non-limiting example, this is represented in the equation shown below.

[0418]

[0419] The measure of instantaneous patient ventilation (V o ) can be multiplied by one minute to represent patient minute ventilation. The measure of instantaneous patient ventilation can be filtered over time to generate a measure of patient ventilation that can be used to determine patient attachment. The measure of patient ventilation can be a measure of volume. The measure of patient ventilation can be represented by The filter coefficient can be set such that data related to approximately one minute is used. A longer filter coefficient can be used to make the determination of patient attachment more reliable, but this configuration can be slower to react to patient attachment and detachment.

[0420] At step 2616, the controller generates a measure of total signal fluctuation. The measure of total signal fluctuation can include noise generated by electronics of the respiratory system, signal noise, environment, patient breathing, patient ventilation, patient movement, and / or other noise originating from or not originating from the patient. The controller can generate a measure of instantaneous total signal fluctuation from the flow parameter variation data generated at step 2608. The controller can generate a measure of instantaneous total signal fluctuation (which can also be described as fluctuation or average fluctuation) by taking an absolute value of the flow parameter variation data. In one non-limiting example, this is represented in the equation shown below.

[0421]

[0422] In one configuration, each data point used for compensation can instead be made positive by taking the square of the flow parameter variation data. However, taking the square of the flow parameter variation data may result in erroneous patient attachment determinations due to random outliers in the flow parameter variation data. Using absolute values ​​may be more tolerant to outliers in the flow parameter variation data, which may be caused by coughing, yawning, etc. Similar to V o , the instantaneous total signal fluctuation value (V 短 ) times one minute. The measure of instantaneous total signal fluctuation can be considered to represent the total fluctuation in the flow parameter variation data resulting from both the patient signal and random noise.

[0423] Similar to V o , which can be used to measure the fluctuation of the instantaneous total signal over time (V 短 ) to generate a measure of total signal fluctuation that is useful for determining patient attachment. The measure of total signal fluctuation can be obtained by The filter factor can be set so that data related to approximately one minute is used. A longer filter factor can be used to make the determination of patient attachment more reliable, but the configuration may be slower to react to attachment and detachment of the patient. In one configuration, the patient ventilation measurement value A measure of the total signal fluctuation that can be greater than or equal to This measure can be greater than or equal to 0. Since the measure of patient ventilation May be primarily related to the patient's minute ventilation, while the measure of total signal fluctuation It may be related to both the patient's minute ventilation and random noise, so in step 2618, the controller can determine the patient's attachment by comparing these two values, such as Figure 27 and 28.

[0424] Determine attachment status

[0425] like Figure 25B As shown, the controller can use the above-mentioned filter characteristics to determine four categories of patient attachment status, namely whether the patient has been detached from the respiratory system, is being attached, is attached, or is being detached. This assessment can be made by comparing the primary filter characteristic to one or more characteristic thresholds (such as, for example, thresholds close to or slightly below 1 as described above). In order to make a determination as to whether the patient is attached or detached, the primary filter characteristic must be above or below the threshold. The threshold can be determined by further analyzing the recent change in the primary filter characteristic, the sum of the recent changes in conductance previously calculated, and / or the value of the characteristic (if the signal comprises pure noise, i.e., a known value of the characteristic when the patient is not attached).

[0426] At decision step 2530, the controller can determine whether the patient was previously attached to the respiratory system or in the process of being detached from the respiratory system (i.e., still attached to the respiratory system). If the patient was not previously attached or was in the process of being detached, i.e., if the patient has been detached or is in the process of being attached, at step 2542, the controller can determine whether the primary filtration feature is greater than a first threshold value or whether the patient has been attached for a predetermined amount of time. If the primary filtration feature is greater than the first threshold value or if the patient has been attached to the respiratory system for at least the predetermined amount of time, at step 2550, the controller can determine that the patient has been attached to the respiratory system.

[0427] If the primary filtration feature is not greater than the first threshold value and / or if the patient has not been attached to the respiratory device for at least the predetermined amount of time, at step 2544, the controller can determine whether the primary filtration feature is greater than a second threshold value that is lower than the first threshold value. If the primary filtration feature is less than the second threshold value, at step 2546, the controller can determine that the patient has been detached. If the primary filtration feature is greater than the second threshold value but not greater than the first threshold value (i.e., between the first threshold value and the second threshold value), at step 2548, the controller can determine that the patient is in the process of being attached to the respiratory system.

[0428] If the patient was previously attached or was in the process of being detached, at step 2532, the controller can determine whether the primary filtration feature is less than a third threshold value or whether the patient has been in the process of being detached for a predetermined amount of time. If the primary filtration feature is lower than the third threshold value or if the patient has been detached for at least the predetermined amount of time, at step 2534, the controller can determine that the patient has been detached.

[0429] If the primary filtration feature is not lower than the third threshold value and / or if the patient has not been detached for at least the predetermined amount of time, at step 2536, the controller can determine whether the primary filtration feature is lower than a fourth threshold value that is higher than the third threshold value. If the primary filtration feature is lower than the fourth threshold value but not lower than the third threshold value (i.e., between the third threshold value and the fourth threshold value), at step 2538, the controller can determine that the patient is in the process of being detached from the respiratory system. If the primary filtration feature is not lower than (or higher than) the fourth threshold value, at step 2540, the controller can determine that the patient has been attached.

[0430] The first threshold value and the fourth threshold value can be the same or different (e.g., the fourth threshold value can be lower than the first threshold value). The second threshold value and the fourth threshold value can be the same or different (e.g., the fourth threshold value can be lower than the second threshold value). The absolute values of the difference between the first threshold value and the second threshold value and the difference between the third threshold value and the fourth threshold value can be the same or different.

[0431] Figure 25BThe process shown in FIG1 ensures that the controller does not make a determination that a patient has been attached or detached based on the primary filter characteristic briefly crossing a threshold by a small amount, for example, by determining that the patient is still in the process of being attached or detached from the respiratory system. If the primary filter characteristic crosses the threshold, but not by a significant amount, the patient is determined to be attaching or detaching. Furthermore, if the patient is determined to be attaching or detaching for a certain amount of time, the determination can be switched to attaching or detaching without requiring the primary filter characteristic to be significantly above or below the characteristic threshold.

[0432] like Figure 27 As shown, the controller can use the above reference Figure 26 Generated measure of patient ventilation and a measure of the total signal fluctuation To determine the patient attachment status, for example, whether the patient is attached or detached from the breathing system. A measure of the total signal fluctuation To make this determination. If the patient's ventilation measurement and a measure of the total signal fluctuation Similarly, the controller can determine that most of the signal changes are caused by the patient and, therefore, the patient is attached or connected. and a measure of the total signal fluctuation Significantly different (e.g. ), the controller can determine that most of the signal variations are caused by random noise and, therefore, the patient is not attached or connected.

[0433] In one configuration, if the measure of instantaneous patient ventilation (V o ) and a measure of the total signal fluctuation (V 短 ) are similar, the controller can determine that most of the signal changes are caused by the patient and, therefore, the patient is attached or connected. In one configuration, if the measure of instantaneous patient ventilation (V o ) and a measure of the instantaneous total signal fluctuation (V 短 ) are significantly different (e.g., V 短 >>V o ), the controller can determine that most of the signal variations are due to random noise and, therefore, the patient is not attached or connected. A measure of the fluctuation of the total signal The relationship between can be represented by a patient connection measure (σ), which can be represented by (or partially include) and In one non-limiting example, the following equation can be used to calculate the patient connection measure value (σ).

[0434]

[0435] The patient connection measure (σ) can be determined in part by using a correction factor. The patient connection measure (σ) can be determined by comparing two or more measures of instantaneous patient ventilation (V o ) to determine the correction factor, each measurement is calculated by a different method. It can be done by comparing two or more measurements of the patient's ventilation. To determine the correction factor, each measurement value is calculated by a different method. In one configuration, the correction factor can be used as an indicator of the smoothness of the patient's respiratory flow. The patient connection measurement value (σ) can be related to the signal-to-noise ratio (SNR). In a non-limiting example, this relationship can be represented by the following equation.

[0436]

[0437] When the signal-to-noise ratio (SNR) is zero, the patient connection measure value (σ) may be zero. When the signal-to-noise ratio (SNR) approaches zero, the patient connection measure value (σ) may approach zero. When the signal-to-noise ratio (SNR) is infinite, the patient connection measure value (σ) may be one. When the signal-to-noise ratio (SNR) approaches infinity, the patient connection measure value (σ) may approach one. The patient connection measure value (σ) may be used to determine patient attachment by comparing the patient connection measure value (σ) with one or more thresholds. The controller may also alternatively determine whether the patient is attached to the respiratory system by comparing any of the patient connection measure value, the correction factor, any measure of the patient's minute ventilation, or any combination thereof with a specific threshold. The combination may be based on an average or any weighted average. The correction factor and / or the measure of minute ventilation tend to zero when the patient has detached, and therefore should exceed a certain threshold if the patient is attached to the respiratory system.

[0438] like Figure 27 As shown, at decision step 2702, the controller may determine whether the patient was previously attached or detached from the respiratory system. If the patient was previously detached, then at step 2704, the controller may determine a patient connection measure (σ) (the patient connection measure may be, for example, a measure of the patient's ventilation). A measure of the fluctuation of the total signal The controller then determines whether the patient connection measure (σ) exceeds the attachment threshold. If the patient connection measure (σ) exceeds the attachment threshold, the controller determines that the patient is attached in step 2706. If the patient connection measure (σ) does not exceed the attachment threshold, the controller determines that the patient is detached in step 2708. The attachment threshold can be set to a value corresponding to the signal-to-noise ratio, above which it can be reliably assumed that the fluctuations are not entirely generated by random noise.

[0439] In one configuration, the attachment threshold can be set to a value corresponding to a signal-to-noise ratio of 33%. In one configuration, the attachment threshold can be set to a value corresponding to a signal-to-noise ratio below or above 33%. In one configuration, at step 2704, the controller can determine whether the patient connection measurement value (σ) continuously exceeds the attachment threshold or another threshold for a set time period. The time period can be such that data for a short time period (such as a few seconds) will have decayed by the end of the time period, such as by about 80%. This can advantageously prevent a few seconds of erroneous data from causing an incorrect determination of patient attachment.

[0440] If the patient was previously attached, then in step 2710, the controller may determine whether the patient connection measure value (σ) has dropped below the detachment threshold. If the patient connection measure value (σ) has dropped below the detachment threshold, the controller determines in step 2714 that the patient has detached. If the patient connection measure value (σ) has not dropped below the detachment threshold, the controller determines in step 2712 that the patient is attached. The detachment threshold is lower than the attachment threshold. The detachment threshold may be set to a value at which it can be reliably assumed that the variation is caused solely by random noise. In one configuration, in step 2710, the controller may determine whether the patient connection measure value (σ) has continuously dropped below the detachment threshold for a set time period. The time period may be such that data for a short time period (such as a few seconds) will have decayed by the end of the time period. This may advantageously prevent a few seconds of erroneous data from causing an incorrect determination of patient attachment.

[0441] like Figure 28 As shown, the controller can use the patient connection measure (σ) to determine four categories of patient attachment status, namely, whether the patient is detached from the respiratory system, being attached, attached, or being detached. This assessment can be made by comparing the patient connection measure (σ) (also described as a ratio) to one or more thresholds. In order to determine whether the patient is attached or detached, the patient connection measure (σ) must be above or below the threshold.

[0442] At decision step 2830, the controller can determine whether the patient was previously attached to the respiratory system or in the process of being detached from the respiratory system (i.e., still attached to the respiratory system). If the patient was not previously attached or was in the process of being detached, i.e., if the patient has been detached or is in the process of being attached, at step 2842, the controller can determine whether the patient connection metric value (σ) is greater than a first threshold value or whether the patient has been attached for a predetermined amount of time. If the patient connection metric value (σ) is greater than the first threshold value or if the patient has been attached to the respiratory system for at least the predetermined amount of time, at step 2850, the controller can determine that the patient has been attached to the respiratory system.

[0443] If the patient connection metric value (σ) is not greater than the first threshold value and / or if the patient has not been attached to the respiratory device for at least the predetermined amount of time, at step 2844, the controller can determine whether the patient connection metric value (σ) is greater than a second threshold value that is lower than the first threshold value. If the patient connection metric value (σ) is less than the second threshold value, at step 2846, the controller can determine that the patient has been detached. If the patient connection metric value (σ) is greater than the second threshold value but not greater than the first threshold value (i.e., between the first threshold value and the second threshold value), at step 2848, the controller can determine that the patient is in the process of being attached to the respiratory system.

[0444] If the patient was previously attached or was in the process of being detached, at step 2832, the controller can determine whether the patient connection metric value (σ) is less than a third threshold value or whether the patient has been in the process of being detached for a predetermined amount of time. If the patient connection metric value (σ) is lower than the third threshold value or if the patient has been detached for at least the predetermined amount of time, at step 2834, the controller can determine that the patient has been detached.

[0445] If the patient connection metric value (σ) is not lower than the third threshold value and / or if the patient has not been detached for at least the predetermined amount of time, at step 2836, the controller can determine whether the patient connection metric value (σ) is lower than a fourth threshold value that is higher than the third threshold value. If the patient connection metric value (σ) is lower than the fourth threshold value but not lower than the third threshold value (i.e., between the third threshold value and the fourth threshold value), at step 2838, the controller can determine that the patient is in the process of being detached from the respiratory system. If the patient connection metric value (σ) is not lower than (or higher than) the fourth threshold value, at step 2840, the controller can determine that the patient has been attached.

[0446] The first threshold value and the fourth threshold value can be the same or different (e.g., the fourth threshold value can be lower than the first threshold value). The second threshold value and the fourth threshold value can be the same or different (e.g., the fourth threshold value can be lower than the second threshold value). The absolute values of the difference between the first threshold value and the second threshold value and the difference between the third threshold value and the fourth threshold value can be the same or different.

[0447] Figure 28 The processes illustrated in the middle ensure that the controller does not make a decision that the patient is attached or detached based on the patient connection metric value (σ) briefly crossing the threshold by a small amount, for example. If the patient connection metric value (σ) crosses the threshold, but not by a significant amount, the patient is determined to be in the process of attaching or in the process of detaching. Furthermore, if the patient is determined to be in the process of attaching or in the process of detaching for some amount of time, the determination can switch to attached or detached without requiring the patient connection metric value (σ) to be significantly above or below the characteristic threshold.

[0448] Reference is made to Figure 27 and Figure 28 The systems and methods described can be more reliable in determining patient attachment than the systems and methods described in reference to Figure 25A and 25B The systems and methods described can be more reliable in determining patient attachment than the systems and methods described in reference to

[0449] Generating an alternative metric value for patient ventilation

[0450] The controller can generate an alternative metric value (V) for patient ventilation based on the patient connection metric value (σ) and a metric value for the total signal fluctuation The controller can generate an alternative metric value (V) for patient ventilation based on the patient connection metric value (σ) and a metric value for the total signal fluctuation The controller can generate an alternative metric value (V) for patient ventilation based on the patient connection metric value (σ) and a metric value for the total signal fluctuation

[0451]

[0452] The function used can be generated through machine learning using the metric values detailed herein in combination with actual metric values for patient ventilation.

[0453] A surrogate measure of patient ventilation (V) can be related to actual minute ventilation of the patient and other factors, such as profile of the flow path and / or flow restrictions in the respiratory system, such as between the cannula and the patient's nose. In one configuration, actual minute ventilation of the patient cannot be calculated from the surrogate measure of patient ventilation (V) alone, but requires a factor measure. In one configuration, the surrogate measure of patient ventilation (V) can be converted to or close to actual minute ventilation of the patient by other factors, such as profile of the flow path, flow restrictions in the respiratory system, and / or other factors. Changes in the surrogate measure of patient ventilation (V) for the same patient with the same nasal cannula can be related to actual changes in actual minute ventilation of the patient. Thus, trends in the surrogate measure of patient ventilation (V) can be used to indicate similar trends in actual minute ventilation of the patient. In addition, analyzing trends in minute ventilation can incorporate a determination of patient attachment, such that trends in minute ventilation are evaluated using only the surrogate measure of patient ventilation (V) corresponding to time periods when the patient is determined to be attached. The surrogate measure of patient ventilation (V) can have additional uses that help efficient use of the respiratory system.

[0454] Example Application of Breath Detection Process

[0455] Determining whether a patient is attached to a patient interface can inform the accuracy of respiratory rate determinations and / or for other purposes. One of the other purposes is a process for adherence tracking. Adherence tracking is an important factor for gauging patient compliance, especially for insurance reimbursement purposes. Adherence tracking informs a user, clinician, insurance provider, or other person whether the patient is attached and is part of a compliance measurement that informs whether the patient is using the prescribed therapy as intended. To strive for patient compliance, that is, to overestimate patient compliance is preferred over underestimating patient compliance, any time that the patient is detected to be attached to the patient interface can be logged in an electronic memory of the respiratory device as a moment of adherence to therapy.

[0456] The respiratory device can record the total amount of time that the patient is attached to the device and / or record the device on time, where adherence is a percentage of the duration of the device on time. The device can log the duration of each patient attachment state category. Data related to adherence can also be selectively accessible through a higher level settings menu. The menu can be password encrypted to prevent the patient from accessing the menu and / or otherwise protected. The compliance data can also be optionally recorded for transmission to a server and / or available for download by connecting the respiratory device to a second device, such as a computer or USB.

[0457] The respiratory device can generate an alarm when the patient becomes detached. The alarm can be generated immediately or after a preset time after it is determined that the patient has become detached. The preset time can be between about 10 seconds and about 10 minutes, or between about 30 seconds and 5 minutes, or between about 1 minute and about 2 minutes. The alarm can additionally be output to a nurse call port. After the alarm is generated, the device can provide a user with an option to confirm whether the patient has detached from the device, e.g., via a user interface of the respiratory device. If the patient is still attached to the device, the user can use the option to manually override the controller’s determination that the patient has detached. The override option can reduce false positive detections, e.g., in cases where the patient can be attached to the device but shallowly breathing. The controller of the device can use the patient attachment determination to determine whether to display certain parameters. For example, the controller can receive an estimate of the patient’s respiratory rate, and can display the respiratory rate estimate if the patient is determined to be attached. The controller can also cause a determination of whether the patient is attached to be displayed. For example, the device can display the respiratory rate estimate if the patient is determined to be attached, and can display a symbol and / or notification that the patient attachment cannot be confirmed if the patient is not determined to be attached. This can improve the reliability of the displayed respiratory frequency estimate.

[0458] If the patient is determined to be attached, the device can also attempt to synchronize the delivery of gas with the patient’s breathing. Breathing synchronization can include adjusting a flow source, such as a flow generator, to have a phase that matches a phase of the patient’s breathing cycle, such as by increasing the flow when the patient inhales and / or decreasing the flow when the patient exhales. The patient’s breathing cycle can be determined using one or more measured parameters, such as flow, blower motor speed, and / or system pressure. Additional details of breathing synchronization can be found in International Patent Publication No. WO 2017 / 200394, filed May 17, 2017, which is incorporated by reference herein in its entirety.

[0459] The device can be configured such that it only suspends recording of certain patient parameters when the patient has disengaged. The patient parameters can include an oxygen efficiency, which can be calculated based on a measured blood oxygen saturation (Sp02) of the patient and a measured fraction of delivered oxygen (Fd02) value to the patient. The oxygen efficiency can be determined based on the measured Sp02 of the patient divided by the measured Fd02. The oxygen efficiency can also be determined based on a non-linear relationship between the measured Sp02 of the patient and the measured Fd02. The device can utilize the oxygen efficiency to control the flow of gases, implementing one or more closed loop control systems. The patient disengagement detection can also be fed into the oxygen delivery control, such as a closed loop control. If the patient temporarily removes the patient interface, the patient's oxygen saturation can decrease, and the controller of the breathing device can begin to increase the oxygen concentration in the mixture of gases to be delivered to the patient. The device can automatically adjust the Fd02 in order to achieve a target Sp02 value for the patient. When the patient interface is reattached to the patient, the oxygen concentration in the flow of gases can be high, which can cause the patient's oxygen saturation to peak and be harmful to the patient. The patient disengagement detection can be factored into the oxygen delivery control of the device such that when the patient is determined to be disengaged from the device, the controller does not begin to increase the oxygen delivery or the controller switches to a specific value. The device can also be configured to shut off a valve to stop the delivery of oxygen or other breathable gas to be mixed with air when it is determined that the patient has disengaged. Shutting off the valve to the oxygen or other breathable gas inlet can reduce the cost of providing therapy and / or improve user safety.

[0460] Additionally or alternatively, the device can be configured to reduce the flow rate, reduce or turn off power to the heating element of the humidification chamber, and / or reduce or turn off power to the heating element of the patient breathing conduit upon determining that the patient has disengaged. The reduction in flow rate can reduce noise. The reduction in flow rate and / or reduction or turning off of power to the heating element(s) of the humidification chamber and / or patient breathing conduit can reduce power consumption of the device, thereby extending battery life and / or the life of another power source of the device. Additionally or alternatively, the device can be configured to increase the flow rate for an initial period of time upon the patient being determined to have disengaged. The increased flow rate can improve the reliability of the patient detection process. The initial period of time of increased flow rate can serve to confirm that the patient has in fact disengaged from the device, i.e., reduce false positives. If the controller determines that the patient has disengaged at the higher flow rate, the device can take the other operations described above (e.g., deactivate certain control algorithms, output an alarm, reduce the flow rate, reduce or turn off power to the heating element of the humidification chamber and / or patient breathing conduit, etc.). The initial period of time can be, for example, between about 10 seconds and about 10 minutes, or between about 30 seconds and 5 minutes, or between about 1 minute and about 2 minutes. The device can resume normal operation upon detecting that the patient has reattached to the respirator, e.g., increase the flow rate and / or turn on power to the heating element of the humidification chamber and / or patient breathing conduit, etc.

[0461] the term

[0462] Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of "including, but not limited to".

[0463] While the disclosure has been described in the context of certain embodiments and examples, those skilled in the art will understand that the disclosure extends beyond the specifically disclosed embodiments to other alternative embodiments and / or uses and obvious modifications and equivalents thereof. Moreover, although the best mode has been disclosed for carrying out the disclosure, a wide variety of modifications and alterations are possible and contemplated in which:

[0464] Features, materials, characteristics or groups described in conjunction with a particular aspect, embodiment, or example are to be understood to be applicable to any other aspect, embodiment or example described in this section or elsewhere in this specification unless incompatible therewith. All features disclosed in this specification, and / or all steps of any method or process so disclosed, can be replaced by alternative features and / or steps, except insofar as the exclusion of such alternatives is explicitly stated to be essential. The application is not restricted to the details of the foregoing embodiments. The application extends to any novel one, or any novel combination, of the features disclosed in this specification, including any novel one, or any novel combination, of the steps of the methods or processes so disclosed.

[0465] Furthermore, certain features described in the context of separate implementations can also be implemented in combination, in a single implementation. Conversely, various features described in the context of a single implementation can also be implemented separately or in any suitable sub-combination. Moreover, although features can be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claim can be

[0466] Furthermore, while certain operations can be described or depicted in the drawings or in the specification in a particular, sequential order, such operations need not be performed in the specified order, or in sequential order, or at all, and that certain operations can be performed in parallel or in any order. Other operations that are not depicted or described can be incorporated into these example methods and processes. For example, one or more additional operations can be performed before, after, simultaneously with, or between any of the described operations. Further, the actions in these processes can be rearranged or reordered according to other implementations. Those skilled in the art will understand that the actual steps taken in the processes shown and / or disclosed in this specification can differ from those shown in the drawings, depending on the embodiment. Depending on the embodiment, certain of the steps described above can be removed, others can be added, and the sequence of steps can be altered. Also, the various system components shown in the above-described implementations can be combined into a single product or packaged into multiple products. These and other examples of the disclosure will be apparent to those of ordinary skill in the art, and can be achieved with the features, components, and / or functions described in this specification and with structures, components, and / or materials suitable for use in implementing such structures, components, and / or functions.

[0467] For purposes of this disclosure, certain aspects, advantages, and novel features are described. It is to be understood that not necessarily all such advantages can be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the disclosure can be practiced without some or all of the advantages to be

[0468] Conditional language such as, among others, "can," "could," "might" or "may," unless specifically stated otherwise, generally are intended to convey that some embodiments include, while other embodiments do not include, certain features, elements and / or steps. Thus, such conditional language generally is not intended to imply that features, elements and / or steps are in any way required in one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements and / or steps are included or are to be performed in any particular embodiment.

[0469] As used herein, degree language such as the words "approximately," "about," "substantially," and "essentially" are used to describe values that are close to the stated value, but still have the desired function or result. For example, the terms "approximately," "about," "substantially," and "essentially" can refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, or within less than 0.01% of a stated amount.

[0470] The scope of the disclosure is not intended to be limited by the specific disclosure herein of the examples in this section or elsewhere in this specification, and can be defined by the claims as presented below, as can be presented in future claims, and as can be amended from time to time. The language of the claims will be construed in light of the language used in the specification and by the context of the disclosure, and, where the claims are ambiguous, they will be interpreted as if the patent applicant is using the broadest reasonable interpretation of the claim language.

Claims

1. A respiratory system configured to deliver respiratory therapy to a patient, the respiratory system comprising: A breathing apparatus, comprising: a flow generator configured to generate a flow of gas for delivery to a patient; A controller, wherein the controller is configured to: receiving data of a first parameter of a flow of gas, the first parameter being indicative of respiration of the patient; generating flow parameter change data based on the data of the first parameter; generating a measure of patient ventilation based on the flow parameter change data; generating a measure of total signal fluctuation based on the flow parameter change data; and The patient's attachment to the respiratory apparatus is determined based on a comparison between the measure of the patient's ventilation and the measure of the total signal fluctuation.

2. The breathing system according to claim 1, wherein The first parameter indicates a flow rate or a flow rate.

3. A breathing system according to claim 1 or claim 2, wherein: The controller is further configured to receive data of a second parameter representative of performance of a component of the respiratory apparatus, and wherein the flow parameter change data is generated by subtracting an estimated effect of the second parameter from the measured value of the first parameter, and wherein the component of the respiratory apparatus is a blower of a flow generator, the blower comprising a motor.

4. The breathing system according to claim 3, wherein: The second parameter is indicative of the motor speed of the blower motor or is indicative of the motor speed of the blower motor.

5. The breathing system according to claim 1 or 2, wherein: The controller is further configured to generate data representing a plurality of measures of instantaneous patient ventilation from the flow parameter change data, and wherein the measure of patient ventilation is generated by filtering the data representing a plurality of measures of instantaneous patient ventilation.

6. The breathing system of claim 5, wherein: The controller is further configured to select a portion of the flow parameter change data for use in generating a measure of each instantaneous patient ventilation.

7. The breathing system of claim 6, wherein: Each measure of instantaneous patient ventilation is generated by fitting one or more functions to a selected portion of the flow parameter change data, generating a curve based on the fitted one or more functions, and integrating the absolute value of the curve generated by the fitted one or more functions.

8. The breathing system of claim 7, wherein: The controller is configured to perform a least squares fit to fit the one or more functions to the selected portion of the flow parameter variation data.

9. The breathing system according to claim 1 or 2, wherein: The controller is further configured to generate data representing a measure of a plurality of instantaneous total signal fluctuations from the flow parameter change data, and wherein the measure of the total signal fluctuations is generated by filtering the data representing the measure of a plurality of instantaneous total signal fluctuations.

10. The breathing system of claim 9, wherein: The measure of each instantaneous total signal fluctuation is determined by obtaining the absolute value of the flow parameter change data.

11. The breathing system according to claim 1 or 2, wherein: Comparing the measure of patient ventilation and the measure of total signal fluctuation includes obtaining a ratio between the measure of patient ventilation and the measure of total signal fluctuation.

12. The breathing system according to claim 1 or 2, wherein: The breathing system is a non-sealed system configured to deliver nasal high flow therapy.

13. The breathing system of claim 1 or 2, comprising a humidifier configured to humidify the flow of gas to the patient.

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